Fix building on modern versions of Xcode and OS X.

Recent versions of XCode fail to compile the adb and fastboot binaries due to
two functions being deprecated in 10.9 (GetCurrentProcess and
ProcessInformationCopyDictionary), and the use of -Werrror.

This patch replaces the method implementations which use calls to methods
deprecated in the 10.9 SDK with versions which only call non-deprecated methods.

Return path including executable instead of without

The previous implementation returned the path the executable was in instead
of returning the path including the executable (i.e. it returned ...bin
instead of ...bin/executable). This is not what the original methods did
and caused the process forking of adb to fail.

This patch corrects the implementation.

Remove explict use of ASCII encoding

Replace the use of CFStringGetCString with kCFStringEncodingASCII specified
with CFStringGetFileSystemRepresentation which will ensure the correct
character encoding is used to conver the CFString into a NULL terminated
char array suitable for use with POSIX APIs.
Change-Id: Ibab1dc05c4f4db8604d329a493b4241992b8e69d

Change-Id: I855bf26aff45093ca9022924f3ecd1b80f2305a8