Use the full path when outputting the `.gcda' file.
Use the full path when outputting the `.gcda' file.

If we compile a single source program, the `.gcda' file will be generated where
the program was executed. This isn't desirable, because that place may be at an
unpredictable place (the program could call `chdir' for instance).

Instead, we will output the `.gcda' file in the same place we output the `.gcno'
file. I.e., the directory where the executable was generated. This matches GCC's
behavior.

<rdar://problem/13061072> & PR11809


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@178084 91177308-0d34-0410-b5e6-96231b3b80d8

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