${x//y/} is a bash syntax. Replace with something dash compatible

RP 2015/5/3
Upstream-Status: Pending

Index: DirectFB-1.7.7/configure.in
===================================================================
--- DirectFB-1.7.7.orig/configure.in
+++ DirectFB-1.7.7/configure.in
@@ -2696,7 +2696,7 @@ AM_CONDITIONAL(BUILD_TOOLS, test "$with_
 AM_CONDITIONAL(CROSS_COMPILING, test "$cross_compiling" = "yes")
 
 CFLAGS="$CFLAGS $DFB_INTERNAL_CFLAGS"
-CXXFLAGS="$CXXFLAGS ${CFLAGS//-Werror-implicit-function-declaration/}"
+CXXFLAGS="$CXXFLAGS $(printf '%s\n' "$CFLAGS" | sed 's/-Werror-implicit-function-declaration//g')"
 DFB_LDFLAGS="$LDFLAGS $ZLIB_LIBS"
 
 CFLAGS="$CFLAGS $CFLAGS_STD"