Implement simple filter-out mechanism for libraries.

Signed-off-by: Garrett Cooper <yanegomi@gmail.com>
diff --git a/lib/Makefile b/lib/Makefile
index 10d8d6a..df6908e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -28,6 +28,8 @@
 CFLAGS			+= -D_USC_LIB_ -D__UCLIBC__ -DUCLINUX
 endif
 
+FILTER_OUT_LIBSRCS	:= mount_utils.c
+
 LIB			:= libltp.a
 
 pc_file			:= $(DESTDIR)/$(datarootdir)/pkgconfig/ltp.pc