HDFFV-8653
replace non-standard sizeof in the fortran tests with c_sizeof
(1) Removed the overloaded h5_sizeof functions for characters and integer arrays since Sun compilers don't allow them to be passed into a function that uses sizeof.
(2) Requested min. precision for reals to avoid duplicate interfaces when the flag -r8 (or equiv.) is set.
tested:
*jam: intel, -i8 -r8 --enable-fortran2003
*jam: pgi, --enable-fortran2003
*emu: sun, --enable-fortran2003