Remove unused third_party/talloc

third_party/talloc/README.chromium

-Name: talloc
-URL: http://talloc.samba.org/talloc/doc/html/index.html
-Version: 2.0.1
-License: LGPL v3
-Security Critical: yes
-
-The talloc library is only being used by a portion of the Mesa
-software renderer, in ../mesa/MesaLib, and is only linked in to the
-OSMesa shared library.
-
-This is version 2.0.1 of talloc, with the following modifications (see
-chromium.patch):
-
- - #include "replace.h" was commented out in talloc.c.
- - "bool malloced" was changed to "int malloced" in talloc.c.
- - #include string.h, and conditional #include of stdint.h, were added
-   to talloc.h.
- - Uses of the "inline" keyword were made conditional and disabled on
-   Windows.
- - A "min_size" inline function was used in place of the MIN macro.
- - An implementation of strnlen was provided for platforms not
-   supporting it (in particular, Mac OS X).
- - A use of ssize_t was changed to size_t on Windows.
- - a call to vsnprintf() querying the required buffer size was changed to use
-   ptr NULL size 0 in order to satisfy MSVC