Give configure ability to set CFLAGS/LDFLAGS later

Some CFLAGS/LDFLAGS may disrupt the configure script's operation,
in particular santization and fuzzer options that break assumptions
about memory and file descriptor dispositions.

This adds two flags to configure --with-cflags-after and
--with-ldflags-after that allow specifying additional compiler and
linker options that are added to the resultant Makefiles but not
used in the configure run itself.

E.g.

env CC=clang-3.9 ./configure \
  --with-cflags-after=-fsantize=address \
  --with-ldflags-after="-g -fsanitize=address"

0 files changed, 0 insertions, 0 deletions