bash/flex: Ensure BUILD_FLAGS doesn't leak onto target

The ptest packages were leaking BUILD_LDFLAGS into the Makefile used
on target. Remove these values instead.

(From OE-Core rev: 599132c7794a1192ddd257669798a3ec6d1191bb)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/flex/flex_2.6.4.bb

@@ -68,6 +68,7 @@ do_install_ptest() {
 	sed -e 's,--sysroot=${STAGING_DIR_TARGET},,g' \
 	    -e 's|${DEBUG_PREFIX_MAP}||g' \
 	    -e 's:${HOSTTOOLS_DIR}/::g' \
+	    -e 's:\(^LDFLAGS_FOR_BUILD =\).*:\1:g' \
 	    -e 's:${RECIPE_SYSROOT_NATIVE}::g' \
 	    -e 's:${BASE_WORKDIR}/${MULTIMACH_TARGET_SYS}::g' \-e 's/^Makefile:/_Makefile:/' \
 	    -e 's/^srcdir = \(.*\)/srcdir = ./' -e 's/^top_srcdir = \(.*\)/top_srcdir = ./' \