Move javac_wrapper.sh scripts into own files.

I have originally created those snippets as minimal
change from the previous bash-functions.

On second thought, rather than generate those files,
it is cleaner to just create those files in source.

The build script will use "javac_wrapper.sh" if it exists.

Test: check that generated run-test data is unchanged
Change-Id: Ibd0d92cf399c3026be127ac42b513382c04142f7
diff --git a/test/run-test-build.py b/test/run-test-build.py
index 03ac18f..f8eb283 100755
--- a/test/run-test-build.py
+++ b/test/run-test-build.py
@@ -66,7 +66,8 @@
     "SOONG_ZIP":   join(build_top, "prebuilts/build-tools/linux-x86/bin/soong_zip"),
     "ZIPALIGN":    join(build_top, "prebuilts/build-tools/linux-x86/bin/zipalign"),
     "JAVA":        join(java_home, "bin/java"),
-    "JAVAC":       join(java_home, "bin/javac") + " -g -Xlint:-options -source 1.8 -target 1.8",
+    "JAVAC":       join(java_home, "bin/javac"),
+    "JAVAC_ARGS":  "-g -Xlint:-options -source 1.8 -target 1.8",
     "D8":          join(tools_dir, "d8"),
     "HIDDENAPI":   join(tools_dir, "hiddenapi"),
     "JASMIN":      join(tools_dir, "jasmin"),