Continue the cleanup started on r158737

Adds a utility class method to TestBase that checks and removes a temp
file.
Removed every use of system() to execute rm -f.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@158809 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed