Some Perl compile options affects ABI and not using them while compiling
our module resulted in non-working build.
Notably on 32-bit Debian 10, Perl is built with -D_FILE_OFFSET_BITS=64
and our module after being compiled without this option caused segmentation
faults in unexpected places.
It's surplus option because the perl executable returns the proper path.
Also the Perl module configure script was cleaned up a bit.
Note that NXT_PERL_LDOPTS already contains the library path.
