Was sed in ebuild. Extracted for clarity.
--- a/Makefile.in
+++ b/Makefile.in
@@ -57,7 +57,6 @@
 ###########################################################################
 
 # For compile
-CC=@CC@
 # For copy
 CP=cp
 @CP@
@@ -83,7 +82,7 @@
 
 # For linking (configure script will modify this line)
 # xmkmf et imake informations are take into account.
-LIBS = @LIBS@ -lm
+LIBS = @LIBS@ -lm -lX11
 
 all:demo
 
@@ -93,8 +92,7 @@
 CFLAGS = -DSCOREDIR=\"$(SCOREDIR)\" \
 	 -DRESOURCEDIR=\"$(RESOURCEDIR)\" \
 	 -DXBLVERSION=\"$(XBLVERSION)\" \
-	 -DGROUP_GID=$(GROUP_GID) \
-	  $(USE_SETGID) @DEFS@ @CFLA@ -g
+	  $(USE_SETGID) @DEFS@ @CFLA@ $(GENTOO_CFLAGS)
 # For link edit options
 LDOPTIONS=$(CFLAGS)
 LDOPTIONS=@LDOPTIONS@