Ninja: Restore detection of msvc-wine showIncludes prefix

Since commit 8f82e755f3 (Ninja: Fix detection of MSVC showIncludes
prefix in Italian, 2023-01-26, v3.26.0-rc1~20^2) our regex no longer
matches the output from `msvc-wine`, which uses forward slashes:

    Note: including file: /path/to/foo.h

`cl /showIncludes` under Wine prints paths of the form `Z:\path\to\file`,
but the `msvc-wine` wrapper converts them to the form `/path/to/file` so
that native Ninja can be used.  Update our regex to match the prefix
followed by a path with a leading forward slash.

Fixes: #24908

1 files changed, 8 insertions, 0 deletions

diff --git a/Tests/RunCMake/showIncludes.c b/Tests/RunCMake/showIncludes.c
index 5afe04a..7d467cf 100644
--- a/Tests/RunCMake/showIncludes.c
+++ b/Tests/RunCMake/showIncludes.c
@@ -36,6 +36,14 @@ int main()
     }
   }
 
+  // msvc-wine (special case for test, not a real VS value).
+  if (strcmp(vslang, "msvc-wine") == 0) {
+    if (cp == 437 || cp == 65001) {
+      printf("Note: including file: /c/foo.h\n");
+      return 0;
+    }
+  }
+
   // German.
   if (strcmp(vslang, "1031") == 0) {
     if (cp == 437 || cp == 65001) {