use _GNU_SOURCE instead of _DEFAULT_SOURCE for older glibc

diff --git a/build/unix/Makefile b/build/unix/Makefile
index c1df0d0..d7ca532 100644 (file)
--- a/build/unix/Makefile
+++ b/build/unix/Makefile
@@ -59,7 +59,7 @@ PFSOURCE = $(PFBASESOURCE) $(IO_SOURCE)
 VPATH = .:$(CSRCDIR):$(CSRCDIR)/posix:$(CSRCDIR)/stdio:$(CSRCDIR)/win32_console:$(CSRCDIR)/win32
 
 XCFLAGS = $(CCOPTS)
-XCPPFLAGS = -DPF_SUPPORT_FP -D_DEFAULT_SOURCE
+XCPPFLAGS = -DPF_SUPPORT_FP -D_GNU_SOURCE
 XLDFLAGS = $(WIDTHOPT)
 
 CPPFLAGS = -I. $(XCPPFLAGS)