Revert "[analyzer] scan-build: support spaces in compiler path and arguments."

This reverts commit r236423 and its followup r236533, as indiscriminate
quoting makes for too much quoting (and clang doesn't like both '"-c"'
and -D"FOO=bar").


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@236562 91177308-0d34-0410-b5e6-96231b3b80d8