pv: fix build issue with some toolchains

While 'pv' uses autoconf, it does not use automake for its
makefiles. It uses $(LD) $(LDFLAGS) to achieve partial linking, but
using 'ld' directly doesn't work well with some toolchain
configuration, as the ld default emulation may not necessarily be the
correct one. By passing custom values for LD and LDFLAGS, we ensure
that 'gcc' is used to do these partial linking steps.

Fixes the following build failures (x86-64 and mips64) :

  http://autobuild.buildroot.org/results/9ac/9aca276a220ad1460e5b32bd042dd4c93649baf3/build-end.log
  http://autobuild.buildroot.org/results/910/91044c01dcc3c4150aa6e74f5964fff27b9dac79/build-end.log

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pv/pv.mk

@@ -9,6 +9,15 @@ PV_SOURCE = pv-$(PV_VERSION).tar.bz2
 PV_SITE = http://www.ivarch.com/programs/sources
 PV_LICENSE = Artistic-2.0
 PV_LICENSE_FILES = doc/COPYING
-PV_MAKE_OPT = LD=$(TARGET_LD) # otherwise 'ld' is used
+
+# While 'pv' uses autoconf, it does not use automake for its
+# makefiles. It uses $(LD) $(LDFLAGS) to achieve partial linking, but
+# using 'ld' directly doesn't work well with some toolchain
+# configuration, as the ld default emulation may not necessarily be
+# the correct one. By passing the below values for LD and LDFLAGS, we
+# ensure that 'gcc' is used to do these partial linking steps.
+PV_MAKE_OPT = \
+	LD=$(TARGET_CC) \
+	LDFLAGS="-Wl,-r -nostdlib"
 
 $(eval $(autotools-package))