hdf5_ep

[svn-r17248] Bug fix (1301 & 1468)

PathScale was mistaken as the Gcc compiler such that gcc flags were added
to it but PathScale did not honor many of them. (e.g. -Wvariadic-macros,
-Wold-style-definition, -Winit-self, -Wvariadic-macros, -Wmissing-include-dirs,
-Winit-self, -Wc++-compat)

Solution:
Added a pre-condition to detect pathScale compiler before Gcc is
accepted.

Tested:
Sandia Glory where PathScale compiler is available.