Workaround for older clang compiler bug.
Workaround for older clang compiler bug.

The libmesh assertion macros fail to parse on older clang compilers. We'll
juse fall back to the previous behavior when using those compilers.

roystgnr/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,dschwen/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,dschwen/libmesh,capitalaslash/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh,dschwen/libmesh,jwpeterson/libmesh,dschwen/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,dschwen/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,capitalaslash/libmesh,libMesh/libmesh,libMesh/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,roystgnr/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,roystgnr/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,libMesh/libmesh,roystgnr/libmesh,libMesh/libmesh,libMesh/libmesh