Update to use C99 instead of C11 because of lack of SGX support

Author: billphipps

IDE/LINUX-SGX/sgx_t_static.mk

@@ -115,7 +115,7 @@ ifeq ($(HAVE_WOLFSSL_SP), 1)
 endif
 
 
-Flags_Just_For_C := -Wno-implicit-function-declaration -std=c11
+Flags_Just_For_C := -Wno-implicit-function-declaration -std=c99
 Common_C_Cpp_Flags := $(SGX_COMMON_CFLAGS) -nostdinc -fvisibility=hidden -fpie -fstack-protector $(Wolfssl_Include_Paths) -fno-builtin-printf -I.
 Wolfssl_C_Flags := $(Flags_Just_For_C) $(Common_C_Cpp_Flags) $(Wolfssl_C_Extra_Flags)