Turn of -Werror by default

Don't build with -Werror unless asked to.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211299 91177308-0d34-0410-b5e6-96231b3b80d8
Add option to keep flavor out of the install directory

Sometimes we want to install things in "standard" locations and the
flavor directories interfere with that.  Add an option to keep them
out of the install path.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211300 91177308-0d34-0410-b5e6-96231b3b80d8
Remove bogus configure check

Configure creates makefiles, so it doesn't make sense to check for
them to see if we can configure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211301 91177308-0d34-0410-b5e6-96231b3b80d8