Log Message:
ladspa: Correct injection of CFLAGS, CXXFLAGS, LDFLAGS

Patch the upstream makefile to rename CFLAGS, CXXFLAGS, LDFLAGS to
LOCAL_*. Retrieve  CFLAGS, CXXFLAGS, LDFLAGS from pkgsrc.

This package uses homegrown hardcoded macros for libraries (-fPIC), this
is not portable and should be adjusted in future.

This unbreaks build on NetBSD/amd64 8.99.7 as of today.