build, meson, gitlab: Generate native .pdb CodeView symbols on Windows

Reverts dc21fb76

The CodeView format introduces some advantages to our Windows build:
- It is way smaller than DWARF, reducing the .exe installer. With
  the strip of COFF symbols too, the installation is 120MB smaller.
- Can be uploaded as .appxsym to be used on demand by MSIX (in thesis)
- Works better with DIA and DbgHelp debuggers like WinDbg and DrMingW,
  respectively. LLDB also works by using LLDB_USE_NATIVE_PDB_READER=1

Context: that was not working before because DrMingw and LLDB seems to
only search for the build-time .pdb path in '.buildid' section of bins.
See: https://github.com/jrfonseca/drmingw/issues/91 and
https://github.com/llvm/llvm-project/issues/125355. So, we will set
_NT_SYMBOL_PATH at least for $PREFIX/bin for now as workaround.

libgimp/gimp.c

@@ -226,10 +226,17 @@ gimp_main (GType  plug_in_type,
   /* Use Dr. Mingw (dumps backtrace on crash) if it is available. */
   {
     time_t   t;
+    gchar   *codeview_path;
     gchar   *filename;
     gchar   *dir;
     wchar_t *plug_in_backtrace_path_utf16;
 
+    /* FIXME: https://github.com/jrfonseca/drmingw/issues/91 */
+    codeview_path = g_build_filename (gimp_installation_directory (),
+                                      "bin", NULL);
+    g_setenv ("_NT_SYMBOL_PATH", codeview_path, TRUE);
+    g_free (codeview_path);
+
     /* This has to be the non-roaming directory (i.e., the local
      * directory) as backtraces correspond to the binaries on this
      * system.