dotest - Refactored some code into loops

Renamed 'base' to 'lldbRootDirectory'
Renamed 'lldbPath' to 'lldbPythonDir'
Added cmake output directories to lldb executable search locations
Fixed invocation of lldb -P to ignore 'Cannot read termcap database'

Differential Revision: http://reviews.llvm.org/D9818

llvm-svn: 237601