Add --enable-petsc-required configure option.
Add --enable-petsc-required configure option.

Add test for no petsc when --enable-petsc-required.

vikramvgarg/libmesh,vikramvgarg/libmesh,vikramvgarg/libmesh,pbauman/libmesh,svallaghe/libmesh,capitalaslash/libmesh,capitalaslash/libmesh,90jrong/libmesh,giorgiobornia/libmesh,svallaghe/libmesh,vikramvgarg/libmesh,vikramvgarg/libmesh,balborian/libmesh,friedmud/libmesh,pbauman/libmesh,dschwen/libmesh,aeslaughter/libmesh,dschwen/libmesh,friedmud/libmesh,libMesh/libmesh,jwpeterson/libmesh,dschwen/libmesh,hrittich/libmesh,hrittich/libmesh,friedmud/libmesh,friedmud/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,90jrong/libmesh,dschwen/libmesh,giorgiobornia/libmesh,hrittich/libmesh,friedmud/libmesh,balborian/libmesh,roystgnr/libmesh,balborian/libmesh,BalticPinguin/libmesh,friedmud/libmesh,libMesh/libmesh,roystgnr/libmesh,giorgiobornia/libmesh,pbauman/libmesh,hrittich/libmesh,giorgiobornia/libmesh,pbauman/libmesh,balborian/libmesh,jwpeterson/libmesh,libMesh/libmesh,pbauman/libmesh,benkirk/libmesh,90jrong/libmesh,benkirk/libmesh,giorgiobornia/libmesh,giorgiobornia/libmesh,libMesh/libmesh,svallaghe/libmesh,svallaghe/libmesh,benkirk/libmesh,friedmud/libmesh,BalticPinguin/libmesh,roystgnr/libmesh,capitalaslash/libmesh,svallaghe/libmesh,balborian/libmesh,dschwen/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,hrittich/libmesh,aeslaughter/libmesh,pbauman/libmesh,capitalaslash/libmesh,svallaghe/libmesh,benkirk/libmesh,roystgnr/libmesh,friedmud/libmesh,capitalaslash/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,capitalaslash/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,benkirk/libmesh,aeslaughter/libmesh,pbauman/libmesh,libMesh/libmesh,jwpeterson/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,aeslaughter/libmesh,aeslaughter/libmesh,hrittich/libmesh,90jrong/libmesh,90jrong/libmesh,balborian/libmesh,BalticPinguin/libmesh,aeslaughter/libmesh,libMesh/libmesh,aeslaughter/libmesh,balborian/libmesh,balborian/libmesh,friedmud/libmesh,jwpeterson/libmesh,pbauman/libmesh,benkirk/libmesh,90jrong/libmesh,balborian/libmesh,hrittich/libmesh,libMesh/libmesh,90jrong/libmesh,aeslaughter/libmesh,pbauman/libmesh,aeslaughter/libmesh,balborian/libmesh,benkirk/libmesh,giorgiobornia/libmesh,vikramvgarg/libmesh,benkirk/libmesh,capitalaslash/libmesh,roystgnr/libmesh,hrittich/libmesh,libMesh/libmesh,vikramvgarg/libmesh,roystgnr/libmesh,BalticPinguin/libmesh,capitalaslash/libmesh,dschwen/libmesh,90jrong/libmesh,svallaghe/libmesh,hrittich/libmesh,dschwen/libmesh,svallaghe/libmesh,jwpeterson/libmesh,svallaghe/libmesh,benkirk/libmesh,90jrong/libmesh,BalticPinguin/libmesh,dschwen/libmesh