blob.hpp dimension check code problem

[qiulinzhang]

Issue summary

blob.hpp offset dimension check code problem Line 157 I think should check CHECK_GE(c, 0), while not CHECK_GE(channels(), 0); also the last 2 lines, line 159 and line 161, for width and height

Steps to reproduce

Tried solutions

System configuration

• Operating system:
• Compiler:
• CUDA version (if applicable):
• CUDNN version (if applicable):
• BLAS:
• Python version (if using pycaffe):
• MATLAB version (if using matcaffe):

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