Change the internal interface to makeNameProper to take a bool that

Change the internal interface to makeNameProper to take a bool that
indicates whether the label is private or not, instead of taking
prefix stuff.  One effect of this is that symbols will be generated
with *just* the private prefix, instead of both the private prefix
*and* the user-label-prefix, but this doesn't matter as long as it
is consistent.  For example we'll now get "Lfoo" instead of "L_foo".
These are just assembler temporary labels anyway, so they never even
make it into the .o file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75607 91177308-0d34-0410-b5e6-96231b3b80d8