Autodetect SLEPc from PETSC_DIR if users do not set SLEPC_DIR
Autodetect SLEPc from PETSC_DIR if users do not set SLEPC_DIR

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