Add a few new methods to FileSpec to make it a little easier to work
with directories, without increasing the size of the FileSpec object.
GetPath() returns a std::string of the full pathname of the file.
IsDirectory(), IsPipe(), IsRegularFile(), IsSocket(), and IsSymbolicLink()
can be used instead of getting the FileType() and comparing it to an enum.

Update PlatformDarwinKernel to use these new methods.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@180704 91177308-0d34-0410-b5e6-96231b3b80d8
Add a final fall-back to PlatformDarwin::GetDeveloperDirectory() which
will run xcode-select --print-path to find the currently selected 
Xcode developer directory.  Mostly useful for when lldb is not being run out
of the /Applications/Xcode.app bundle so it can't locate the iOS or
kernel SDKs.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@180705 91177308-0d34-0410-b5e6-96231b3b80d8
When lldb stops in a stack frame where we have source level information (file, line number), don't
print the disassembly context around $pc -- just print the filename and line number, even if we 
can't show the source code.  Previously if the source file was not available, lldb would print
the source filename & line number and assembly.  
<rdar://problem/13072951> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@180706 91177308-0d34-0410-b5e6-96231b3b80d8