Find perl using the CMake's standard FindPerl module.

This gives a standard PERL_EXECUTABLE configuration knob which is useful for
specifying a perl to use without having it in PATH.

Change-Id: I4b196b77e0b4666081a3f291fee3654c47925844
Reviewed-on: https://boringssl-review.googlesource.com/3570
Reviewed-by: Adam Langley <agl@google.com>
3 files changed