Keep track of artificial scopes introduced by line directives. For example,

Keep track of artificial scopes introduced by line directives. For example,

#line 41 "bar.c"
  dummy (1, i);
#line 24 "bar.h"
  i = f2 (i);
#line 44 "bar.c"

This is tested by step-line.exp in gdb testsuite.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@109189 91177308-0d34-0410-b5e6-96231b3b80d8