This fixes a regression from 450c358881dbc6dcfb2692b8f4debb7db8fdc54b; after testing for -Wl,-z,defs, CFLAGS was restored from an incorrect variable, leaving CFLAGS essentially empty.
This would break builds for e.g. arm with Clang, where -mthumb would be essential for being able to build some inline assembly snippets correctly.
This also had the effect of dropping the default "-g -O2" arguments from CFLAGS.
Signed-off-by: Martin Storsjö martin@martin.st