Revert r127073: "Introduce $(ECHOPATH) to print DOSish path string on MSYS bash for...

Revert r127073: "Introduce $(ECHOPATH) to print DOSish path string on MSYS bash for alternative of $(ECHO)."

It broke the llvm-gcc-native-mingw32 buildbot, and we need all of them to be green for the 2.9 branch.

Takumi, please reapply after we branch, preferably with a fix ;-)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127107 91177308-0d34-0410-b5e6-96231b3b80d8