mismatched DR and drmem release/debug won't build

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on February 14, 2011 12:02:57_

if you build drmem w/ "cmake -DDEBUG=ON" w/ internal DR, you enable Debug
config for DR, but default Release for drmem, and both show up as configs
in VS. then the build default ends up as Debug and drmem fails b/c has
Debug subdirs.

=> should warn w/ mismatch
=> maybe change default to Debug

_Original issue: http://code.google.com/p/drmemory/issues/detail?id=294_