pass top level configure cflags into spandsp too

libs/spandsp/configure.ac

@@ -21,6 +21,10 @@
 AC_PREREQ([2.59])
 AC_INIT([spandsp], [1.99.0])
 
+CFLAGS="$CFLAGS $CONFIGURE_CFLAGS"
+CXXFLAGS="$CXXFLAGS $CONFIGURE_CXXFLAGS"
+LDFLAGS="$LDFLAGS $CONFIGURE_LDFLAGS"
+
 SPANDSP_LT_CURRENT=3
 SPANDSP_LT_REVISION=0
 SPANDSP_LT_AGE=0