scripts: get_abi.pl: precompile what match regexes

In order to earn some time during matches, pre-compile regexes.

Before this patch:
	$ time ./scripts/get_abi.pl undefined |wc -l
	6970

	real	0m54,751s
	user	0m54,022s
	sys	0m0,592s

Afterwards:

	$ time ./scripts/get_abi.pl undefined |wc -l
	6970

	real	0m5,888s
	user	0m5,310s
	sys	0m0,562s

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/ec45de8fcae791aab0880644974a110424423e68.1632411447.git.mchehab+huawei@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>