icu: tweak icu-config exec_prefix output

Closes #3259

We need to tweak icu-config's exec_prefix too, otherwise if the host
system lacks icu the build fails when looking for the libraries in
/usr/lib rather than the staging directory.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/icu/icu.mk

@@ -16,7 +16,9 @@ ICU_SUBDIR = source
 HOST_ICU_SUBDIR = source
 
 define ICU_PREFIX_FIXUP
-	$(SED) "s,^default_prefix=.*,default_prefix=\'$(STAGING_DIR)/usr\',g" $(STAGING_DIR)/usr/bin/icu-config
+	$(SED) "s,^default_prefix=.*,default_prefix=\'$(STAGING_DIR)/usr\',g" \
+		-e "s,^exec_prefix=.*,exec_prefix=\'$(STAGING_DIR)/usr\',g" \
+		$(STAGING_DIR)/usr/bin/icu-config
 endef
 
 ICU_POST_INSTALL_TARGET_HOOKS += ICU_PREFIX_FIXUP