build: Set QCOM global cflags for secondary arch

Change-Id: I637d94f9b0ddee2c8d6057de44355e482163dd36
build: Fix copypasta in 2nd target clang flags

Change-Id: Ieedce8754b145e53d72a5d6a4b41fbe5cdf6473f
build: Add chromium prebuilt support to envsetup.sh && The core Makefile
Prebuilt chromium: Run a check for target device directory

this should fix the issue that arises if device fails and device is built again,
chromium will error out because it thinks the prebuilt files exist (which they are
not, directories are just created).

Signed-off-by: Ayysir <ayysir@aospal.com>
Change-Id: I595cab268e66c738ccae9900150b36d7f9626a6e
Use prebuilt chromium by default
Use -O3 flag
Update roomservice.py