package/linux-tools/perf: add dependency on 32-bit sync builtins

package/linux-tools/perf: add dependency on 32-bit sync builtins

Sync builtins ops are strictly required by perf utility as it uses
atomic_xxx() functions.

Otherwise building fails like that:
|.../output/host/opt/ext-toolchain/bin/../lib/gcc/arc-snps-linux-uclibc/8.2.1/../../../../arc-snps-linux-uclibc/bin/ld:
|.../output/build/linux-5.0.7/tools/perf/libperf.a(libperf-in.o): in function `atomic_cmpxchg':
|.../output/build/linux-5.0.7/tools/include/asm-generic/atomic-gcc.h:69: undefined reference to `__sync_val_compare_and_swap_4'

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[Thomas: drop Config.in comment]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>