commit 78b6eebcf1b33c71ae5028422f500a0e48b20544
Author: Stefan Liebler <stli@linux.vnet.ibm.com>
Date:   Mon Mar 24 16:32:47 2014 +0100

    Use += before-compile instead of a :=.

diff --git a/posix/Makefile b/posix/Makefile
index 683b6e4b272fdebb..4034282866139aaa 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -96,7 +96,7 @@ others		:= getconf
 install-bin	:= getconf
 install-others-programs	:= $(inst_libexecdir)/getconf
 
-before-compile	:= testcases.h ptestcases.h
+before-compile	+= testcases.h ptestcases.h
 
 # So they get cleaned up.
 generated := $(addprefix wordexp-test-result, 1 2 3 4 5 6 7 8 9 10) \