for StringRef with a StringMap
The bug is that the empty key compares equal to the tombstone key.
Also added an assertion to DenseMap to catch similar bugs in future.
llvm-svn: 187866
Previously, yaml2coff.cpp had a writeHexData static helper function to
do this, but it is generally useful functionality.
Also, validate hex strings up-front to avoid running having to handle
errors "deep inside" the yaml2obj code (it also gives better diagnostics
than it used to).
llvm-svn: 183345