Silence warnings under clang/llvm


git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12083 b70326c6-7e19-0410-871a-916f4a2858ee
Quiet clang/llvm warnings


git-svn-id: http://svn.osgeo.org/postgis/branches/2.1@12084 b70326c6-7e19-0410-871a-916f4a2858ee