Revert "Allow more generic platform names for linux based platforms."

We need a better solution to find out if we are building on a 64bit system.

This reverts commit 58806890

.

Change-Id: I43c48b5cbc5e96f93b65165b0445670a832b0206
Reviewed-by: Jani Heikkinen <jani.heikkinen@digia.com>

tools/qmake/mkspecs/features/functions.prf

 defineTest(isPlatformSupported) {
   static: return(false)
-  !equals(QMAKE_HOST.arch, "x86_64"): return(false)
   osx:lessThan(QMAKE_XCODE_VERSION, 5.1): return(false)
 
-  linux|win32-msvc2013|macx-clang: return(true)
+  linux-g++|win32-msvc2013|macx-clang: return(true)
+  android-g++-b2qt: return(true)
   return(false)
 }