busybox: fix build on SPARC and SPARC64

Since we introduced the support for building Busybox as individual
binaries, Busybox started failing to build on SPARC/SPARC64 with this
feature enabled:

appletlib.c:(.text.find_applet_by_name+0x14): relocation truncated to fit: R_SPARC_GOT13 against symbol `applet_nameofs' defined in .rodata.applet_nameofs section in libbb/lib.a(appletlib.o)
appletlib.c:(.text.find_applet_by_name+0x18): relocation truncated to fit: R_SPARC_GOT13 against symbol `applet_names' defined in .rodata.applet_names section in libbb/lib.a(appletlib.o)
[...]

This commit adds two patches to Busybox to fix this issue, by adding
-fPIC to CFLAGS when building on SPARC/SPARC64. The patches have been
submitted upstream.

Fixes:

  http://autobuild.buildroot.net/results/90144369ccea8c41ec7643a79a7ebfaa9b7db95c/



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