[petsc-dev] clash of --download-xxx with something in /usr/include /usr/local/include

[Barry Smith]

   When one runs for example --download-hd5f but there are hdf5 include files in /usr/include or /usr/local/include different compile stages, for example for different external packages, may use the wrong include files leading to very confusing failed builds. 

   Is there any systematic tests we could add in configure that could detect this type of potential problem and error out or warn?

   Thanks

   Barry