Stop linking pthread.

It was only needed by gtest, which is no longer used.
(Intesting note: I checked when the -lpthread flag was added, and it's
been around since the first revision of build.ninja, which used to be
checked in before configure.py existed. Back then, it looks like '@' was
used to dereference built-in variables, and build outputs were also
prefixed by '@'!).

diff --git a/configure.py b/configure.py
index 6d4c4d4..eacf5a0 100755 (executable)
--- a/configure.py
+++ b/configure.py
@@ -513,8 +513,6 @@ if platform.is_windows():
     for name in ['includes_normalize_test', 'msvc_helper_test']:
         objs += cxx(name)
 
-if not platform.is_windows():
-    test_libs.append('-lpthread')
 ninja_test = n.build(binary('ninja_test'), 'link', objs, implicit=ninja_lib,
                      variables=[('libs', test_libs)])
 n.newline()