build system cleanup: rename FEATURE_AWK_MATH to FEATURE_AWK_LIBM;
 disable parsing test applet.

diff --git a/libbb/parse_config.c b/libbb/parse_config.c
index a0599d4..9a85786 100644
--- a/libbb/parse_config.c
+++ b/libbb/parse_config.c
@@ -9,7 +9,7 @@
 
 #include "libbb.h"
 
-#if ENABLE_PARSE
+#if defined ENABLE_PARSE && ENABLE_PARSE
 int parse_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int parse_main(int argc UNUSED_PARAM, char **argv)
 {