[sconscript.platform] 优化针对编译器判断的脚本

- 删除啰嗦的代码
related: https://github.com/RT-Thread/rt-thread/issues/3046

bsp/stm32/stm32l475-atk-pandora/board/ports/fal/SConscript

@@ -10,13 +10,12 @@ src     += Glob('*.c')
 CPPPATH = [cwd]
 LOCAL_CCFLAGS = ''
 
-if rtconfig.CROSS_TOOL == 'gcc':
+if rtconfig.PLATFORM == 'gcc':
+    LOCAL_CCFLAGS += ' -std=c99'
+elif rtconfig.PLATFORM == 'armcc':
+    LOCAL_CCFLAGS += ' --c99'
+elif rtconfig.PLATFORM == 'armclang':
     LOCAL_CCFLAGS += ' -std=c99'
-elif rtconfig.CROSS_TOOL == 'keil':
-    if rtconfig.PLATFORM == 'armcc':
-        LOCAL_CCFLAGS += ' --c99'
-    elif rtconfig.PLATFORM == 'armclang':
-        LOCAL_CCFLAGS += ' -std=c99'
 
 group = DefineGroup('FAL', src, depend = ['PKG_USING_FAL'], CPPPATH = CPPPATH, LOCAL_CCFLAGS = LOCAL_CCFLAGS)
 

components/drivers/spi/SConscript

@@ -25,13 +25,12 @@ if GetDepend('RT_USING_SFUD'):
     CPPPATH += [cwd + '/sfud/inc']
     if GetDepend('RT_SFUD_USING_SFDP'):
         src_device += ['sfud/src/sfud_sfdp.c']
-    if rtconfig.CROSS_TOOL == 'gcc':
+    if rtconfig.PLATFORM == 'gcc':
+        LOCAL_CCFLAGS += ' -std=c99'
+    elif rtconfig.PLATFORM == 'armcc':
+        LOCAL_CCFLAGS += ' --c99'
+    elif rtconfig.PLATFORM == 'armclang':
         LOCAL_CCFLAGS += ' -std=c99'
-    elif rtconfig.CROSS_TOOL == 'keil':
-        if rtconfig.PLATFORM == 'armcc':
-            LOCAL_CCFLAGS += ' --c99'
-        elif rtconfig.PLATFORM == 'armclang':
-            LOCAL_CCFLAGS += ' -std=c99'
 
 src += src_device