package/gdb: fix gnulib issue with musl and uClibc toolchains

package/gdb: fix gnulib issue with musl and uClibc toolchains

Starting with gdb 7.11, the bundled gnulib want to use rpl_gettimeofday
(gettimeofday replacement) due bad guessing when cross-compiling with musl
and uClibc toolchains. Instead of patching gnulib configure script to fix
the test, use gl_cv_func_gettimeofday_clobber=no to not use rpl_gettimeofday.

Thanks to Thomas Petazzoni to suggest this patch.

Reported upstream:
https://sourceware.org/bugzilla/show_bug.cgi?id=19798

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>