hdf5_ep

[svn-r5931] 
Purpose:
__DLL__ is a keyword in some platforms and __DLL__ is also defined as a macro for windows DLL applications.
That causes problems.
Description:
Solution:
Use H5_DLL*** to replace __DLL***__ at all header files.
Change the macro defination at H5api_adpt.h.
Platforms tested:
linux2.2.18smp, irix64, solaris 2.7 and windows 2000