configure.ac : Don't zap '-g' from $CFLAGS.
configure.ac : Don't zap '-g' from $CFLAGS.

The '-g' was in-correctly getting zapped from all CFLAGS expressions
including eg:

    -mfloat-gprs=double (for powerpc e500) -> -mfloatprs=double.

Reported-by: Gustavo Zacarias <beac5f8171fcde5e2ec734cc5d25d03e7362e8de@zacarias.com.ar>

waitman/flac,waitman/flac,waitman/flac,waitman/flac,waitman/flac