Set BUILD_ options to 1 instead of just defining them

Makefile.system

@@ -1236,16 +1236,16 @@ ifeq ($(BUILD_HALF), 1)
 CCOMMON_OPT += -DBUILD_HALF
 endif
 ifeq ($(BUILD_SINGLE), 1)
-CCOMMON_OPT += -DBUILD_SINGLE
+CCOMMON_OPT += -DBUILD_SINGLE=1
 endif
 ifeq ($(BUILD_DOUBLE), 1)
-CCOMMON_OPT += -DBUILD_DOUBLE
+CCOMMON_OPT += -DBUILD_DOUBLE=1
 endif
 ifeq ($(BUILD_COMPLEX), 1)
-CCOMMON_OPT += -DBUILD_COMPLEX
+CCOMMON_OPT += -DBUILD_COMPLEX=1
 endif
 ifeq ($(BUILD_COMPLEX16), 1)
-CCOMMON_OPT += -DBUILD_COMPLEX16
+CCOMMON_OPT += -DBUILD_COMPLEX16=1
 endif
 
 CCOMMON_OPT += -DVERSION=\"$(VERSION)\"