[valgrind] compile with -funwind-tables

[gaa]

Description:

Need to add stack unwinding information to have valid stack traces on ARM processors.
Also it is needed to keep symbol table by disabling stripping in PKGBUILD.

Package version: 3.10.1

Steps to reproduce:

Check for EXIDX section in binary
$ objdump -t /usr/bin/valgrind | grep ARM\.exidx

Expected result:
$ objdump -t /usr/bin/valgrind | grep ARM\.exidx
00010710 l d .ARM.exidx 00000000 .ARM.exidx
$

Actual result:
$ objdump -t /usr/bin/valgrind | grep ARM\.exidx
$