Fixes a number of issue related to test portability on Windows.

99% of this CL is simply moving calls to "import pexpect" to a more
narrow scope - i.e. the function that actually runs a particular
test.  This way the test suite can run on Windows, which doesn't have
pexpect, and the individual tests that use pexpect can be disabled on
a platform-specific basis.

Additionally, this CL fixes a few other cases of non-portability.
Notably, using "ps" to get the command line, and os.uname() to
determine the architecture don't work on Windows.  Finally, this
also adds a stubbed out builder_win32 module.

The full test suite runs correctly on Windows after this CL, although
there is still some work remaining on the C++ side to fix one-shot
script commands from LLDB (e.g. script print "foo"), which currently
deadlock.

Reviewed by: Todd Fiala

Differential Revision: http://reviews.llvm.org/D4573

llvm-svn: 213343
diff --git a/lldb/test/benchmarks/frame_variable/TestFrameVariableResponse.py b/lldb/test/benchmarks/frame_variable/TestFrameVariableResponse.py
index e3acedd..e352108 100644
--- a/lldb/test/benchmarks/frame_variable/TestFrameVariableResponse.py
+++ b/lldb/test/benchmarks/frame_variable/TestFrameVariableResponse.py
@@ -3,7 +3,6 @@
 import os, sys
 import unittest2
 import lldb
-import pexpect
 from lldbbench import *
 
 class FrameVariableResponseBench(BenchBase):
@@ -33,6 +32,7 @@
         print "lldb frame variable benchmark:", self.stopwatch
 
     def run_frame_variable_bench(self, exe, break_spec, count):
+        import pexpect
         # Set self.child_prompt, which is "(lldb) ".
         self.child_prompt = '(lldb) '
         prompt = self.child_prompt