The format of hp file didn't allow double quotes inside strings, and
under prof build, we include args in JOB, which may have double quotes.
When this happens, the error message is confusing to the user. This can
also happen under normal build if the executable name contains double
quite, which is unlikely though.

We fix this issue by introducing escaping for double quotes inside a
string by repeating it twice.

We also fix a buffer overflow bug when the length of the string happen
to be multiple of 5000.

Test Plan:
new tests, which used to fail with error message:

```
hp2ps: "T15904".hp, line 2: integer must follow identifier
```

use new ghc and hp2ps to profile a simple program.

Reviewers: simonmar, bgamari, erikd

Reviewed By: simonmar

Subscribers: rwbarton, carter

GHC Trac Issues: #15904

Differential Revision: https://phabricator.haskell.org/D5346