Fix Linux executable path

Fixes a bug caused by an executable named identically to the directory
it is in, where then the parent of that directory is both on the path
and marked as executable
Avoid this via stat, as we can check we are working with a file which is
executable

core/os/os2/process_linux.odin

@@ -427,7 +427,8 @@ _process_start :: proc(desc: Process_Desc) -> (process: Process, err: Error) {
 			strings.write_string(&exe_builder, executable_name)
 
 			exe_path = strings.to_cstring(&exe_builder) or_return
-			if linux.access(exe_path, linux.X_OK) == .NONE {
+			stat := linux.Stat{}
+			if linux.stat(exe_path, &stat) == .NONE && .IFREG in stat.mode && .IXUSR in stat.mode {
 				found = true
 				break
 			}