perl: Run make depend to fix build race condition

Run make depend before building perl. This fixes build failures on machines with high number of cores.

Example error 1:

/bin/ln -s /build/staging_dir/hostpkg/usr/bin/generate_uudmap generate_uidmap
make[5]: ./generate_uudmap: Command not found
make[5]: *** [Makefile:321: bitcount.h] Error 127

Example error 2:

/bin/ln -s /build/staging_dir/hostpkg/usr/bin/generate_uudmap generate_udmap
./generate_uudmap uudmap.h bitcount.h mg_data.h
/bin/ln: failed to create symbolic link 'generate_uudmap': File exists
make[5]: *** [Makefile:325: generate_uudmap] Error 1

Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=996953

Link: https://salsa.debian.org/perl-team/interpreter/perl/-/commit/366bc98c916a3455f15c532aa33a5636d2fe2803

Closes: https://github.com/openwrt/packages/issues/8238

Signed-off-by: Andreas Gnau andreas.gnau@iopsys.eu