builtins: silence GCC warning

If the builtins are built with libgcc as the unwind provider on ARM, the exposed
_Unwind_SetIP is a macro.  This results in the following warning due to
expansion of the argument:

warning: suggest parentheses around arithmetic in operand of ‘|’ [-Wparentheses]

Add a no-op set of parenthesis around the argument that will prevent this
warning.

llvm-svn: 248686