create hello world test driver to check if posix and syncio both work from phIO

[cwsmith]

pseudo code for header processing

int numberOfNodes[2];
const char* iotype = "binary"
int nfiles[2] = {1,N}; //1: posix mode, >1: syncio mode 
int file = 0;
for(int i=0; i<2; i++) {
  phio_openfile_read("geombc", nfiles, &file);
  phio_readheader(&file, "number of nodes", &(numberOfNodes[i]), 1, "integer", iotype);
  phio_closefile_read(&file);
}
assert( numberOfNodes[0] == numberOfNodes[1] );

[mrasquin]

Commenting about the comment on "nfiles=1: posix mode”.
SyncIO also allows to have one single file that includes the data for all parts.
Would this case still be acceptable with the new interface?

[cwsmith]

Thanks for pointing that out. Using the nfiles arg is not correct. In solver the plan is to count the number of geombc-dat or restart-dat files and use that to determine if we will run in posix or syncio mode. With the mode known the appropriate phIO initialization/registration function will be called to enable it. I am working on that mechanism now.

[cwsmith]

the tests are up cwsmith/phasta@ec2df29