SDL: Add X1 and X2 button support to mouse test

SDL Commits
1 
From 13756b5c72412fad4dea7f7473f0a713757fa6ac Mon Sep 17 00:00:00 2001
From: IOBYTE <[EMAIL REDACTED]>
Date: Fri, 4 Mar 2022 10:47:25 -0500
Subject: [PATCH] Add X1 and X2 button support to mouse test

---
 test/testmouse.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/test/testmouse.c b/test/testmouse.c
index 0c9f7ee1045..c73adca512c 100644
--- a/test/testmouse.c
+++ b/test/testmouse.c
@@ -100,6 +100,8 @@ loop(void *arg)
             case SDL_BUTTON_LEFT:   active->r = 255; buttons |= SDL_BUTTON_LMASK; break;
             case SDL_BUTTON_MIDDLE: active->g = 255; buttons |= SDL_BUTTON_MMASK; break;
             case SDL_BUTTON_RIGHT:  active->b = 255; buttons |= SDL_BUTTON_RMASK; break;
+            case SDL_BUTTON_X1:     active->r = 255; active->b = 255; buttons |= SDL_BUTTON_X1MASK; break;
+            case SDL_BUTTON_X2:     active->g = 255; active->b = 255; buttons |= SDL_BUTTON_X2MASK; break;
             }
             break;
         case SDL_MOUSEBUTTONUP:
@@ -110,6 +112,8 @@ loop(void *arg)
             case SDL_BUTTON_LEFT:   buttons &= ~SDL_BUTTON_LMASK; break;
             case SDL_BUTTON_MIDDLE: buttons &= ~SDL_BUTTON_MMASK; break;
             case SDL_BUTTON_RIGHT:  buttons &= ~SDL_BUTTON_RMASK; break;
+            case SDL_BUTTON_X1:     buttons &= ~SDL_BUTTON_X1MASK; break;
+            case SDL_BUTTON_X2:     buttons &= ~SDL_BUTTON_X2MASK; break;
             }
 
             if (buttons == 0) {