test: adjust the test to improve the viability on Windows

Convert the line endings manually since the parser is sensitive to the
trailing whitespace (the writing of the file will create a `\r\n` rather
than `\n`).  This largely fixes the issues for Windows with the issue
that the processing of the file location is currently not properly
processing escape characters and results in issues.

In theory, it should be possible for `getStringLiteralIfNotInterpolated`
to process the literal segments with `getEncodedStringSegment` for each
segment and then return a literal value cooked.  However, doing so will
require that the function return a `std::string` rather than `StringRef`
since the cooking means that we cannot simply provide a reference to the
SourceManager view.

Author: compnerd

test/SILGen/magic_identifier_file_conflicting.swift.gyb

@@ -1,5 +1,6 @@
 // RUN: %empty-directory(%t)
-// RUN: %gyb -D TEMPDIR=%t %s -o %t/magic_identifier_file_conflicting.swift
+// RUN: %gyb -D TEMPDIR=%t %s > %t/magic_identifier_file_conflicting.swift
+// RUN: %{python} -c "import sys; t = open(sys.argv[1], 'rb').read().replace('\r\n', '\n'); open(sys.argv[1], 'wb').write(t)" %t/magic_identifier_file_conflicting.swift
 
 // We want to check both the diagnostics and the SIL output.
 // RUN: %target-swift-emit-silgen -verify -emit-sorted-sil -enable-experimental-concise-pound-file -module-name Foo %t/magic_identifier_file_conflicting.swift %S/Inputs/magic_identifier_file_conflicting_other.swift | %FileCheck %s
@@ -11,12 +12,14 @@
 
 %{
 TEMPDIR_ESC = TEMPDIR.replace('\\', '\\\\')
+
+import os
 def fixit_loc(start_col, orig_suffix):
   """
   Computes a "start-end" string for a fix-it replacing a string literal which
   starts at start_col and joins orig_suffix to TEMPDIR with a slash.
   """
-  original = '"{0}/{1}"'.format(TEMPDIR, orig_suffix)
+  original = '"{0}"'.format(os.path.join(TEMPDIR, orig_suffix))
   end_col = start_col + len(original)
   return '{0}-{1}'.format(start_col, end_col)
 }%