configure: cleanup petscdir error checks - remove duplicate code and move from petscnagupgrade to petscdir.py

Reported-by: "Williams, Timothy J." zippy@anl.gov

Currently - using PETSC_DIR=. triggers error in generatefortranstubs()

Alternative fix (for fortran stubs):

diff --git a/config/BuildSystem/config/packages/sowing.py b/config/BuildSystem/config/packages/sowing.py
index 50cf56b78b..66349a79e6 100644
--- a/config/BuildSystem/config/packages/sowing.py
+++ b/config/BuildSystem/config/packages/sowing.py
@@ -138,7 +138,8 @@ and run configure again\n')
           sys.path.insert(0, os.path.abspath(os.path.join('lib','petsc','bin','maint')))
           import generatefortranstubs
           del sys.path[0]
-          generatefortranstubs.main(self.petscdir.dir, self.bfort, self.petscdir.dir,0)
+          pdir = os.path.abspath(self.petscdir.dir)
+          generatefortranstubs.main(pdir, self.bfort, pdir, 0)
           if self.fortran.fortranIsF90:
             generatefortranstubs.processf90interfaces(self.petscdir.dir,0)
           self.framework.actions.addArgument('PETSc', 'File creation', 'Generated Fortran stubs')

But then self.petscdir.dir usage in other places might not be appropriate..

PETSc:
  PETSC_ARCH: x86_64
  PETSC_DIR: .