Android patch: Add '--small' option to makeconv call during .ucm to .cnv conversion

This change was introduced in Android by the ICU421 and ICU4.6 upgrades:

https://android.googlesource.com/platform/external/icu/+/85bf2e2
https://android.googlesource.com/platform/external/icu/+/27f6547

In ICU 64 build system has changed, migrating from Makefile to
python script when performing various data transformations, so that patch now
patches BUILDRULES.py and adds '--small' option there.

Test: n/a
Change-Id: If88d126d738c50ed91d55e7695fc133627eca575
diff --git a/icu4c/source/data/BUILDRULES.py b/icu4c/source/data/BUILDRULES.py
index b83577e..a79a915 100644
--- a/icu4c/source/data/BUILDRULES.py
+++ b/icu4c/source/data/BUILDRULES.py
@@ -162,7 +162,10 @@
             input_files = input_files,
             output_files = output_files,
             tool = IcuTool("makeconv"),
-            args = "-s {IN_DIR} -d {OUT_DIR} -c {INPUT_FILE_PLACEHOLDER}",
+            # BEGIN android-changed
+            # args = "-s {IN_DIR} -d {OUT_DIR} -c {INPUT_FILE_PLACEHOLDER}",
+            args = "-s {IN_DIR} -d {OUT_DIR} -c --small {INPUT_FILE_PLACEHOLDER}",
+            # END android-changed
             format_with = {},
             repeat_with = {
                 "INPUT_FILE_PLACEHOLDER": utils.SpaceSeparatedList(file.filename for file in input_files)