[libc] fix a typo (#5689)

Author: mysterywolf

components/libc/compilers/newlib/legacy/_select/SConscript

@@ -8,7 +8,7 @@ cwd   = GetCurrentDir()
 CPPPATH = [cwd]
 group = []
 
-# sys/select.h does not exist in newlib 2.1.0 or lower version
+# sys/select.h does not exist in newlib 2.2.0 or lower version
 if rtconfig.PLATFORM == 'gcc' and (CheckHeader(rtconfig, 'sys/select.h') == False):
     try:
         copy("../../../../common/nogcc/sys/select.h", "./sys/select.h") # copy from 'nogcc/sys/select.h'