Support side by side installation of 32/64 bit plugins.

MOZILLA_PLUGIN_ID needs to be unique for 32/64bit installs to co-exist.
(Tested with WaterFox. the 64bit FireFox)

Signed-off-by: Gordon Smith gordon.smith@lexisnexis.com
Merge pull request #112 from GordonSmith/FB_PLATFORM_ARCH_64

Support side by side installation of 32/64 bit plugins.