Revert "Reapply "[DWARFv5] Emit file 0 to the line table.""
This reverts commit r328676.
Commit r328676 broke the -no-integrated-as flag necessary to build Linux kernel with Clang:
$ cat t.c
void foo() {}
$ clang -no-integrated-as -c t.c -g
/tmp/t-dcdec5.s: Assembler messages:
/tmp/t-dcdec5.s:8: Error: file number less than one
clang-7.0: error: assembler command failed with exit code 1 (use -v to see invocation)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@328699
91177308-0d34-0410-b5e6-
96231b3b80d8