Export the default LOCAL_STRIP_MODULE value

In make, BUILD_PREBUILT and BUILD_SHARED_LIBRARY/BUILD_EXECUTABLE use
different defaults for LOCAL_STRIP_MODULE. Explicitly use the
BUILD_SHARED_LIBRARY/BUILD_EXECUTABLE default so that we'll strip
binaries the same way when converting from Make to Soong.

BUILD_SHARED_LIBRARY/BUILD_EXECUTABLE uses the default set in
dynamic_binary.mk: mini-debug-info.

BUILD_PREBUILT (SHARED_LIBRARIES) uses no_debuglink
BUILD_PREBUILT (EXECUTABLES) doesn't strip by default

None of the above support stripping host modules.

Change-Id: I73a6f7bd7d2ed2033936579c78ae4980386dd4a2