build: enable small-icu support for build-release

On Windows, when building the "build-release" rule, enable both small-icu
and download-all.

This change also slightly refactors the build-release rule, mainly so that
it's easier to read.

The resulting MSI package was tested on Windows 7.

Fixes #9099.

PR: #9100
PR-URL: #9100
Reviewed-By: Steven R. Loomis <srloomis@us.ibm.com>
Reviewed-By: Timothy J Fontaine <tjfontaine@gmail.com>

vcbuild.bat

@@ -37,6 +37,7 @@ set noperfctr_arg=
 set noperfctr_msi_arg=
 set i18n_arg=
 set download_arg=
+set build_release=
 
 :next-arg
 if "%1"=="" goto args-done
@@ -69,7 +70,7 @@ if /i "%1"=="small-icu"     set i18n_arg=%1&goto arg-ok
 if /i "%1"=="full-icu"      set i18n_arg=%1&goto arg-ok
 if /i "%1"=="intl-none"     set i18n_arg=%1&goto arg-ok
 if /i "%1"=="download-all"  set download_arg="--download=all"&goto arg-ok
-if /i "%1"=="build-release" set nosnapshot=1&set config=Release&set msi=1&set licensertf=1&goto arg-ok
+if /i "%1"=="build-release" set build_release=1&goto arg-ok
 
 echo Warning: ignoring invalid command line option `%1`.
 
@@ -82,6 +83,15 @@ goto next-arg
 if defined upload goto upload
 if defined jslint goto jslint
 
+if defined build_release (
+  set nosnapshot=1
+  set config=Release
+  set msi=1
+  set licensertf=1
+  set download_arg="--download=all"
+  set i18n_arg=small-icu
+)
+
 if "%config%"=="Debug" set debug_arg=--debug
 if "%target_arch%"=="x64" set msiplatform=x64
 if defined nosnapshot set nosnapshot_arg=--without-snapshot