Fix OUT_DIR_COMMON_BASE with soong_ui

Currently, Kati is the only one that is respecting OUT_DIR_COMMON_BASE,
causing the build to fail when ninja tries to match up the Soong and
Kati ninja files.

The soong_ui.bash script change is necessary to move the microfactory
built outputs to the correct location.

The config.go change takes care of setting OUT_DIR in the environment of
every subprocess, so that we could remove the OUT_DIR_COMMON_BASE
handling from Make once the USE_SOONG_UI=false path goes away.

Bug: 35929763
Test: m -j blueprint_tools
Test: OUT_DIR=... m -j blueprint_tools
Test: OUT_DIR_COMMON_BASE=... m -j blueprint_tools
Change-Id: I4184f2b4392d32c5bea51e51162a48df0e5c90d5

soong_ui.bash

@@ -57,7 +57,15 @@ function run_go
 
     local mf_src="${TOP}/build/soong/cmd/microfactory"
 
-    local out_dir="${OUT_DIR:-${TOP}/out}"
+    local out_dir="${OUT_DIR-}"
+    if [ -z "${out_dir}" ]; then
+        if [ "${OUT_DIR_COMMON_BASE-}" ]; then
+            out_dir="${OUT_DIR_COMMON_BASE}/$(basename ${TOP})"
+        else
+            out_dir="${TOP}/out"
+        fi
+    fi
+
     local mf_bin="${out_dir}/microfactory_$(uname)"
     local mf_version_file="${out_dir}/.microfactory_$(uname)_version"
     local soong_ui_bin="${out_dir}/soong_ui"