patch 9.1.1379: MS-Windows: error when running evim when space in path

Problem:  MS-Windows: error when running evim when space in path of Vim
Solution: properly parse quoted strings (Miguel Barro)

When vim is installed in a path with whitespaces (like
`C:\Program Files (x86)\Vim\vim91\vim.exe`). Launching `evim` or
`vim -d` will try to open the file ` (x86)\Vim\vim91\vim.exe`.

Modern versions of vim simplify shell operation by parsing its own
command line. For example on Linux all vim flavours like `evim`, `rvim`,
etc are symlinks to vim. Then vim uses the `parse_command_name()`
function to identify which version of vim it should launch.
For `evim` if a GUI is available `gvim` is launched for better user
experience. In order to launch `gvim` the original command line is
parsed to be passed *verbatim* to the new instance.
This parsing did not properly handle quoted command lines with
whitespaces such as
```
"C:\Program Files (x86)\Vim\vim91\vim.exe" -y myfile.txt
```

closes: #17295

Signed-off-by: Miguel Barro <miguel.barro@live.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/gui_w32.c

@@ -5384,13 +5384,11 @@ gui_mch_do_spawn(char_u *arg)
 	{
 	    if (*p == L'"')
 	    {
-		while (*p && *p != L'"')
-		    ++p;
-		if (*p)
-		    ++p;
+		// Skip quoted strings
+		while (*++p && *p != L'"');
 	    }
-	    else
-		++p;
+
+	    ++p;
 	}
 	cmd = p;
     }

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1379,
 /**/
     1378,
 /**/