Support more compilers

Introduce a list of support compilers.
Xcode projects that start with an older version of
Xcode may be configured to use compiler other than
clang. So, this list consists of all compilers
that Xcode 4.5.2 ships with.
Parse log file for working directory

The working directory was assumed to be the folder
of the source file, however, this is not always be
case. Projects that search headers with
$(PROJECT_DIR) placeholder might contain relative
search path from a different directory. In this 
case, we parse build log file for 'cd' commands
and figure out the current working directory.

Thank @PROSPricing for reporting this issue.
Append sources out of current working directory at the bottom of compile_commands.json

libTooling-based tools search for compile_commands.json from the first source path, and cascade lookup parent folders until find it. Pushing sources out of current working directory at the very end of compile_commands.json can guarantee the first source in this file is inside the current working folder or its children folders, which secures OCLint finding the proper compile_commands.json.