gdb: pass gdb_cv_prfpregset_t_broken=no

Starting with glibc 2.25, the proc_service.h header has been copied
from gdb to glibc so other tools can use it. However, that makes it
necessary to make sure that declaration of prfpregset_t declaration
is consistent between gdb and glibc. In gdb, however, there is a
workaround for a broken prfpregset_t declaration in glibc 2.3 which
uses AC_TRY_RUN to detect if it's needed, which doesn't work in
cross-compilation. So pass the cache option to configure.
It needs to be passed to GDB_CONF_ENV to build gdbserver only but
also to GDB_MAKE_ENV, because otherwise it does not get passed to the
configure script of nested packages while building gdbserver with full
debugger.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gdb/gdb.mk

@@ -87,7 +87,21 @@ GDB_CONF_ENV = \
 # not get passed to the configure script of nested packages while
 # building gdbserver with full debugger.
 GDB_CONF_ENV += gl_cv_func_gettimeofday_clobber=no
-GDB_MAKE_ENV = gl_cv_func_gettimeofday_clobber=no
+GDB_MAKE_ENV += gl_cv_func_gettimeofday_clobber=no
+
+# Starting with glibc 2.25, the proc_service.h header has been copied
+# from gdb to glibc so other tools can use it. However, that makes it
+# necessary to make sure that declaration of prfpregset_t declaration
+# is consistent between gdb and glibc. In gdb, however, there is a
+# workaround for a broken prfpregset_t declaration in glibc 2.3 which
+# uses AC_TRY_RUN to detect if it's needed, which doesn't work in
+# cross-compilation. So pass the cache option to configure.
+# It needs to be passed to GDB_CONF_ENV to build gdbserver only but
+# also to GDB_MAKE_ENV, because otherwise it does not get passed to the
+# configure script of nested packages while building gdbserver with full
+# debugger.
+GDB_CONF_ENV += gdb_cv_prfpregset_t_broken=no
+GDB_MAKE_ENV += gdb_cv_prfpregset_t_broken=no
 
 # The shared only build is not supported by gdb, so enable static build for
 # build-in libraries with --enable-static.