SCons: Use CXXFLAGS to disable exceptions, it's only for C++

Following discussion in https://github.com/godotengine/godot-cpp/pull/1216.

(cherry picked from commit 3bfcbe7946fc17d7b61a587bc3dcc8e94633e3d3)

SConstruct

@@ -707,9 +707,9 @@ if selected_platform in platform_list:
         if env.msvc:
             env.Append(CPPDEFINES=[("_HAS_EXCEPTIONS", 0)])
         else:
-            env.Append(CCFLAGS=["-fno-exceptions"])
+            env.Append(CXXFLAGS=["-fno-exceptions"])
     elif env.msvc:
-        env.Append(CCFLAGS=["/EHsc"])
+        env.Append(CXXFLAGS=["/EHsc"])
 
     # Configure compiler warnings
     if env.msvc:  # MSVC

modules/denoise/SCsub

@@ -114,9 +114,9 @@ if env["disable_exceptions"]:
     # OIDN hard-requires exceptions, so we re-enable them here.
     if env.msvc and ("_HAS_EXCEPTIONS", 0) in env_thirdparty["CPPDEFINES"]:
         env_thirdparty["CPPDEFINES"].remove(("_HAS_EXCEPTIONS", 0))
-        env_thirdparty.AppendUnique(CCFLAGS=["/EHsc"])
-    elif not env.msvc and "-fno-exceptions" in env_thirdparty["CCFLAGS"]:
-        env_thirdparty["CCFLAGS"].remove("-fno-exceptions")
+        env_thirdparty.AppendUnique(CXXFLAGS=["/EHsc"])
+    elif not env.msvc and "-fno-exceptions" in env_thirdparty["CXXFLAGS"]:
+        env_thirdparty["CXXFLAGS"].remove("-fno-exceptions")
 
 env_thirdparty.add_source_files(thirdparty_obj, thirdparty_sources)
 env.modules_sources += thirdparty_obj