Refactored lldb executable name discovery

The lldb executable was referenced through the code by 7 different
(effectively) global variables.

global lldbExecutablePath
global lldbExecutable
os.environ['LLDB_EXEC']
os.environ['LLDB_TEST']
dotest.lldbExec
dotest.lldbHere
lldbtest.lldbExec

This change uses one global variable lldbtest_config.lldbExec to
replace them all.

Differential Revision: http://reviews.llvm.org/D9817

llvm-svn: 237600
diff --git a/lldb/test/functionalities/stop-hook/multiple_threads/TestStopHookMultipleThreads.py b/lldb/test/functionalities/stop-hook/multiple_threads/TestStopHookMultipleThreads.py
index 45151cd..35ce2e8 100644
--- a/lldb/test/functionalities/stop-hook/multiple_threads/TestStopHookMultipleThreads.py
+++ b/lldb/test/functionalities/stop-hook/multiple_threads/TestStopHookMultipleThreads.py
@@ -48,7 +48,7 @@
         prompt = "(lldb) "
 
         # So that the child gets torn down after the test.
-        self.child = pexpect.spawn('%s %s %s' % (self.lldbHere, self.lldbOption, exe))
+        self.child = pexpect.spawn('%s %s %s' % (lldbtest_config.lldbExec, self.lldbOption, exe))
         child = self.child
         # Turn on logging for what the child sends back.
         if self.TraceOn():