Revert #48 for Clang
Revert #48 for Clang

When compiling with Clang, don't check the buffer bounds when
generating digits in dtoa_milo. This somehow breaks decimal
placement in the output.

Avoids, but doesn't address the root cause of, #54.

daid/SeriousProton,daid/SeriousProton,daid/SeriousProton,daid/SeriousProton,daid/SeriousProton,daid/SeriousProton