Update the tcmalloc vendor branch to r111 (perftools version 1.8)

third_party/tcmalloc/vendor/NEWS

-== 7 February 2011 ==
+== 15 July 2011 ==
 
+I've just released perftools 1.8
+
+Of the many changes in this release, a good number pertain to porting.
+I've revamped OS X support to use the malloc-zone framework; it should
+now Just Work to link in tcmalloc, without needing
+`DYLD_FORCE_FLAT_NAMESPACE` or the like.  (This is a pretty major
+change, so please feel free to report feedback at
+google-perftools@googlegroups.com.)  64-bit Windows support is also
+improved, as is ARM support, and the hooks are in place to improve
+FreeBSD support as well.
+
+On the other hand, I'm seeing hanging tests on Cygwin.  I see the same
+hanging even with (the old) perftools 1.7, so I'm guessing this is
+either a problem specific to my Cygwin installation, or nobody is
+trying to use perftools under Cygwin.  If you can reproduce the
+problem, and even better have a solution, you can report it at
+google-perftools@googlegroups.com.
+
+Internal changes include several performance and space-saving tweaks.
+One is user-visible (but in "stealth mode", and otherwise
+undocumented): you can compile with `-DTCMALLOC_SMALL_BUT_SLOW`.  In
+this mode, tcmalloc will use less memory overhead, at the cost of
+running (likely not noticeably) slower.
+
+There are many other changes as well, too numerous to recount here,
+but present in the
+[http://google-perftools.googlecode.com/svn/tags/perftools-1.8/ChangeLog ChangeLog].
+
+
+=== 7 February 2011 ===
+
 Thanks to endlessr..., who
 [http://code.google.com/p/google-perftools/issues/detail?id=307 identified]
 why some tests were failing under MSVC 10 in release mode.  It does not look
 like these failures point toward any problem with tcmalloc itself; rather, the
 problem is with the test, which made some assumptions that broke under the
 some aggressive optimizations used in MSVC 10.  I'll fix the test, but in
 the meantime, feel free to use perftools even when compiled under MSVC
 10.
 
-== 4 February 2011 ==
+=== 4 February 2011 ===
 
 I've just released perftools 1.7
 
 I apologize for the delay since the last release; so many great new
 patches and bugfixes kept coming in (and are still coming in; I also
 apologize to those folks who have to slip until the next release).  I
 picked this arbitrary time to make a cut.
 
 Among the many new features in this release is a multi-megabyte
 reduction in the amount of tcmalloc overhead uder x86_64, improved
@@ skipping 149 matching lines @@
 has shown that profiles are unreliable in that case.  The problem has
 existed since the first release of perftools.  We expect to have a fix
 for perftools 1.2.  For more details, see
 [http://code.google.com/p/google-perftools/issues/detail?id=105 issue 105].
 
 Everyone who uses perftools 1.0 is encouraged to upgrade to perftools
 1.1.  If you see any problems with the new release, please file a bug
 report at http://code.google.com/p/google-perftools/issues/list.
 
 Enjoy!