[swift/master] Rename a flang test case

[shahmishal]

On Windows and macOS, the filesystem is case insensitive, and these files
interfere with each other. Reading through, the case of the file extension
is part of the test. I've altered the rest of the name instead.

(cherry picked from commit 6c0a160)
(cherry picked from commit 0a1b111)

[hyp]

LGTM

[davezarzycki]

This change broke unified builds on Fedora 31 (x86_64). What can I do to help debug this?

FAIL: Clang :: Driver/flang/flang.f90 (5010 of 15493)
******************** TEST 'Clang :: Driver/flang/flang.f90' FAILED ********************
Script:
--
: 'RUN: at line 20';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -E                  /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-E /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 25';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -emit-ast           /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-EMIT-AST /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 30';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -fsyntax-only       /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-SYNTAX-ONLY /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 34';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -emit-llvm -S       /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-EMIT-LLVM-IR /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 38';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -emit-llvm          /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-EMIT-LLVM-BC /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 42';   /home/dave/b/u/t/bin/clang --driver-mode=flang -### -S                  /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-S /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
: 'RUN: at line 46';   /home/dave/b/u/t/bin/clang --driver-mode=flang -###                     /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90 2>&1 | /home/dave/b/u/t/bin/FileCheck --check-prefixes=ALL,CHECK-EMIT-OBJ /home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90
--
Exit Code: 1

Command Output (stderr):
--
/home/dave/s/u/llvm-project/clang/test/Driver/flang/flang.f90:16:14: error: ALL-LABEL: expected string not found in input
! ALL-LABEL: "{{[^"]*}}flang" "-fc1"
             ^
<stdin>:1:1: note: scanning from here
clang-9: error: unsupported argument 'flang' to option '--driver-mode='
^
<stdin>:1:31: note: possible intended match here
clang-9: error: unsupported argument 'flang' to option '--driver-mode='
                              ^

[shahmishal]

@davezarzycki I had to cherry-pick #69 from apple/master because test was broken

[davezarzycki]

Ah, well it's broken on Linux too, at least Fedora that is. Want a pull request to disable it?

[shahmishal]

Yes, thanks!