### Issue summary
I know this is a build issue that is not supposed to be here, but it relates to the merge verification procedures that did not catch this **build error**
Merge pull request #6346 from jerryz123/HDF5_config SHA: [e15898a](https://github.com/BVLC/caffe/commit/e15898a06b39a3d2f4dfd0655fac9e56b421534f)
Can not compile in without HDF5 anyway. I suspect you only tried to build it on a target that has HFD5 installed, because in my environment the build fails in 2 places.
I use buildroot to cross compile, Neither my buildhost nor my target has **any** HDF5 stuff installed.
### Steps to reproduce
Build on a host with NO HDF5 references at all !!!!
cmake -DUSE_HDF5=OFF
build will fail
### Suggested Solution
in cmake/Dependencies.cmake
lines 45-48 should have been guarded by the USE_HDF5 sentinel
Cmake fails since no HDF5 stuff is available.
In src /caffe/net.cpp
line 774 the function H5Fis_hdf5 is referenced
Should have been guarded by the USE_HDF5 sentinel