Allow clean compilation of dmg_fp under g++ -Wall -Werror

Allow clean compilation of dmg_fp under g++ -Wall.

We build dmg_fp as part of libbase, which mostly contains our own code.  As
such, we want to build libbase with -Wall -Werror or equivalent.  Since the
gyp model does not allow per-file compilation settings, we can't do this
without modifying dmg_fp or building it into its own library with its own
settings.  The former seems less invasive.

The following gcc warnings are fixed by this patch:
 - suggest parentheses around assignment used as truth value
 - deprecated conversion from string constant to 'char*'
 - comparison between signed and unsigned integer expressions
 - label 'something' defined but not used
 - 'whatever' may be used uninitialized in this function

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=9255

[tony, 2009-02-05 20:48:43]

LGTM.

Can you also create a diff and add it as a .patch file to the directory so it's
easy to update the library in the future?