SDL: project: build in (at least) c99 mode

SDL Commits
1 
From d5479d7b818f2fb620f0f7b3eece4cd87024290a Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Sat, 22 Jul 2023 21:21:28 +0200
Subject: [PATCH] project: build in (at least) c99 mode

---
 CMakeLists.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 47d0fa62bd0f..8e08ac15ee96 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -381,12 +381,14 @@ if(SDL_SHARED)
   add_library(SDL3-shared SHARED)
   add_library(SDL3::SDL3-shared ALIAS SDL3-shared)
   SDL_AddCommonCompilerFlags(SDL3-shared)
+  target_compile_features(SDL3-shared PRIVATE c_std_99)
 endif()
 
 if(SDL_STATIC)
   add_library(SDL3-static STATIC)
   add_library(SDL3::SDL3-static ALIAS SDL3-static)
   SDL_AddCommonCompilerFlags(SDL3-static)
+  target_compile_features(SDL3-static PRIVATE c_std_99)
 endif()
 
 if(SDL_TEST)