Fix build problems on Solaris 10


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@3961 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/common/jpeg/simd/Makefile.am b/common/jpeg/simd/Makefile.am
index 0f1d125..0ccc938 100644
--- a/common/jpeg/simd/Makefile.am
+++ b/common/jpeg/simd/Makefile.am
@@ -53,5 +53,5 @@
 	$(LIBTOOL) --mode=compile --tag NASM ./nasm_lt.sh $(NASM) $(NAFLAGS) $< -o $@
 
 jsimdcfg.inc: jsimdcfg.inc.h ../jpeglib.h ../jconfig.h ../jmorecfg.h
-	$(CPP) $< | grep ^[\;%] | sed 's%_cpp_protection_%%' > $@
+	$(CPP) jsimdcfg.inc.h | $(GREP) ^[\;%] | sed 's%_cpp_protection_%%' > $@