Emit OpenCL local global variables without zeorinitializer

Local variables are not initialized, and every target has
been (incorrectly) ignoring the unnecessary request for
zero initialization.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@221162 91177308-0d34-0410-b5e6-96231b3b80d8
This patch reverts r220496 which issues warning on comparing 
parameters with nonnull attribute when comparison is always
true/false. Patch causes false positive when parameter is
modified in the function.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@221163 91177308-0d34-0410-b5e6-96231b3b80d8