icu-dbg: improve reproducibility

Make sure build host references do not end up being compiled in the image.
This only affects libicutu and icu-dbg.

(From OE-Core rev: e9dfe7eb7f61b909ae7d034e80cfbebc1fad018b)

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-support/icu/icu.inc

@@ -38,6 +38,15 @@ do_configure_prepend_libc-musl () {
     sed -i -e 's,DU_HAVE_STRTOD_L=1,DU_HAVE_STRTOD_L=0,' ${S}/configure.ac
 }
 
+do_compile_prepend_class-target () {
+	# Make sure certain build host references do not end up being compiled
+	# in the image. This only affects libicutu and icu-dbg
+	sed  \
+	    -e 's,DU_BUILD=,DU_BUILD_unused=,g' \
+	    -e '/^CPPFLAGS.*/ s,--sysroot=${STAGING_DIR_TARGET},,g' \
+	    -i ${B}/tools/toolutil/Makefile
+}
+
 PREPROCESS_RELOCATE_DIRS = "${datadir}/${BPN}/${PV}"
 do_install_append_class-native() {
 	mkdir -p ${D}/${STAGING_ICU_DIR_NATIVE}/config