support when cccdlflags uses -fpic (lowercase)

Perl brew on my Debian kFreeBSD box build with -fpic instead of -fPIC.  Not entirely sure why:

```
debiankfreebsd64% perl -MConfig= -E 'say $Config{cccdlflags}'
-fpic
debiankfreebsd64% /usr/bin/perl -MConfig= -E 'say $Config{cccdlflags}'
-fPIC
```

Either way, this patch makes it build a properly relocatable static lib needed for XS / FFI.