Description: Keep C pre processor hardening build flags.  
Author: Martin Steigerwald <martin.steigerwald@proact.de>

--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@
 endif
 
 DEBUGFLAGS = -DFIO_INC_DEBUG
-CPPFLAGS= -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DFIO_INTERNAL $(DEBUGFLAGS)
+CPPFLAGS+= -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DFIO_INTERNAL $(DEBUGFLAGS)
 OPTFLAGS= -g -ffast-math
 FIO_CFLAGS= -std=gnu99 -Wwrite-strings -Wall -Wdeclaration-after-statement $(OPTFLAGS) $(EXTFLAGS) $(BUILD_CFLAGS) -I. -I$(SRCDIR)
 LIBS	+= -lm $(EXTLIBS)
