elfutils: towards uClibc support: argp-standalone usage

elfutils uses the argp family of functions, that isn't available in
uClibc. So, we add a dependency on argp-standalone if building with
uClibc, and modify elfutils source code to link against argp if
needed.

Heavily based from work done by Stefan Fröberg, but with many further
modifications by Thomas Petazzoni.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/elfutils/Config.in

@@ -8,6 +8,10 @@ config BR2_PACKAGE_ELFUTILS
 	depends on BR2_TOOLCHAIN_EXTERNAL_GLIBC || \
 		   BR2_TOOLCHAIN_CTNG_glibc     || \
 		   BR2_TOOLCHAIN_CTNG_eglibc
+	select BR2_PACKAGE_ARGP_STANDALONE if \
+	       BR2_TOOLCHAIN_BUILDROOT   || \
+	       BR2_TOOLCHAIN_CTNG_uClibc || \
+	       BR2_TOOLCHAIN_EXTERNAL_UCLIBC
 	help
 	  Libraries/utilities to handle ELF objects (drop in
 	  replacement for libelf).

package/elfutils/elfutils-02-argp-support.patch

@@ -0,0 +1,92 @@
+Allow the usage of an external implementation of the argp functions
+
+uClibc lack the argp family of functions that glibc has. Therefore, we
+add a check in the configure script to see if argp_parse is available
+in the C library. If not, we look if it is available in the additional
+'argp' library. If so, we link against that library. If not, we error
+out.
+
+This allows to build elfutils against uClibc with an external argp
+library.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+
+Index: b/configure.ac
+===================================================================
+--- a/configure.ac
++++ b/configure.ac
+@@ -269,6 +269,13 @@
+ 	enable_progs=yes)
+ AM_CONDITIONAL(ENABLE_PROGS, test "$enable_progs" = yes)
+ 
++AC_CHECK_FUNC([argp_parse])
++if test "$ac_cv_func_argp_parse" != yes; then
++   AC_CHECK_LIB([argp],[argp_parse],ARGP_LIBS=-largp,
++		AC_MSG_ERROR([No argp_parse function available.]))
++fi
++AC_SUBST(ARGP_LIBS)
++
+ dnl Test for zlib and bzlib, gives ZLIB/BZLIB .am
+ dnl conditional and config.h USE_ZLIB/USE_BZLIB #define.
+ save_LIBS="$LIBS"
+Index: b/src/Makefile.am
+===================================================================
+--- a/src/Makefile.am
++++ b/src/Makefile.am
+@@ -98,26 +98,29 @@
+ # Buggy old compilers.
+ readelf_no_Werror = yes
+ 
+-readelf_LDADD = $(libdw) $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
++readelf_LDADD = $(libdw) $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl \
++	$(ARGP_LIBS)
+ nm_LDADD = $(libdw) $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl \
+-	   $(demanglelib)
+-size_LDADD = $(libelf) $(libeu) $(libmudflap)
+-strip_LDADD = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
+-ld_LDADD = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
++	   $(demanglelib) $(ARGP_LIBS)
++size_LDADD = $(libelf) $(libeu) $(libmudflap) $(ARGP_LIBS)
++strip_LDADD = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl $(ARGP_LIBS)
++ld_LDADD = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl $(ARGP_LIBS)
+ if NATIVE_LD
+ # -ldl is always needed for libebl.
+ ld_LDADD += libld_elf.a
+ endif
+ ld_LDFLAGS = -rdynamic
+-elflint_LDADD  = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
+-findtextrel_LDADD = $(libdw) $(libelf) $(libmudflap)
+-addr2line_LDADD = $(libdw) $(libelf) $(libmudflap)
+-elfcmp_LDADD = $(libebl) $(libelf) $(libmudflap) -ldl
+-objdump_LDADD  = $(libasm) $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
+-ranlib_LDADD = libar.a $(libelf) $(libeu) $(libmudflap)
+-strings_LDADD = $(libelf) $(libeu) $(libmudflap)
+-ar_LDADD = libar.a $(libelf) $(libeu) $(libmudflap)
+-unstrip_LDADD = $(libebl) $(libelf) $(libdw) $(libeu) $(libmudflap) -ldl
++elflint_LDADD  = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl $(ARGP_LIBS)
++findtextrel_LDADD = $(libdw) $(libelf) $(libmudflap) $(ARGP_LIBS)
++addr2line_LDADD = $(libdw) $(libelf) $(libmudflap) $(ARGP_LIBS)
++elfcmp_LDADD = $(libebl) $(libelf) $(libmudflap) -ldl $(ARGP_LIBS)
++objdump_LDADD  = $(libasm) $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl \
++	$(ARGP_LIBS)
++ranlib_LDADD = libar.a $(libelf) $(libeu) $(libmudflap) $(ARGP_LIBS)
++strings_LDADD = $(libelf) $(libeu) $(libmudflap) $(ARGP_LIBS)
++ar_LDADD = libar.a $(libelf) $(libeu) $(libmudflap) $(ARGP_LIBS)
++unstrip_LDADD = $(libebl) $(libelf) $(libdw) $(libeu) $(libmudflap) -ldl \
++	$(ARGP_LIBS)
+ 
+ ldlex.o: ldscript.c
+ ldlex_no_Werror = yes
+Index: b/libdw/Makefile.am
+===================================================================
+--- a/libdw/Makefile.am
++++ b/libdw/Makefile.am
+@@ -111,7 +111,7 @@
+ 		-Wl,--enable-new-dtags,-rpath,$(pkglibdir) \
+ 		-Wl,--version-script,$<,--no-undefined \
+ 		-Wl,--whole-archive $(filter-out $<,$^) -Wl,--no-whole-archive\
+-		-ldl $(zip_LIBS)
++		-ldl $(zip_LIBS) $(ARGP_LIBS)
+ 	if readelf -d $@ | fgrep -q TEXTREL; then exit 1; fi
+ 	ln -fs $@ $@.$(VERSION)
+ 

package/elfutils/elfutils.mk

@@ -25,6 +25,10 @@ ELFUTILS_CONF_ENV += \
         CPPFLAGS="$(filter-out -D_FILE_OFFSET_BITS=64,$(TARGET_CPPFLAGS))"
 endif
 
+ifeq ($(BR2_TOOLCHAIN_BUILDROOT)$(BR2_TOOLCHAIN_EXTERNAL_UCLIBC)$(BR2_TOOLCHAIN_CTNG_uClibc),y)
+ ELFUTILS_DEPENDENCIES += argp-standalone
+endif
+
 ifeq ($(BR2_PACKAGE_ZLIB),y)
  ELFUTILS_DEPENDENCIES += zlib
  ELFUTILS_CONF_OPT += --with-zlib