Changes Autotools testing to use HDF5_TEST_DRIVER environment
variable to avoid running tests that don't work well with several
VFDs
Restores old h5_get_vfd_fapl() testing function to setup a FAPL
with a particular VFD
Adds a macro for the default VFD name
* Strip HD prefix from string/char C API calls
* HD(f)(put|get)(s|c)
* HDstr*
* HDv*printf
* HD(s)(print|scan)f
* HDperror
But NOT:
* HDstrcase*
* HDvasprintf
* HDstrtok_r
* HDstrndup
As those are not C99 and have portability work-around
implementations. They will be handled later.
* Fix th5_system.c screwup
* Adds semicolons to function-like macros
* Adds a do..while(0) loop to some macros
* Removes semicolons when inappropriate, especially H5E_TRY_BEGIN/END
* Implement support for loading of Virtual File Drivers as plugins
Fix plugin caching for VOL connector and VFD plugins
Fix plugin iteration to skip paths that can't be opened
* Enable dynamic loading of VFDs with HDF5_DRIVER environment variable
* Temporarily disable error reporting during H5F_open double file open
* Default to using HDstat in h5_get_file_size for unknown VFDs
* Use macros for some environment variables that HDF5 interprets
* Update "null" and "ctl testing" VFDs
