!251 fix: clang10 lld could not recognized Oz

Merge pull request !251 from MGY917/master

apps/mksh/Makefile

@@ -38,7 +38,7 @@ BUILD_DIR := $(MKSH_DIR)/build
 BUILD_LOG := $(MKSH_DIR)/build.log
 TARGET_OS := OpenHarmony
 
-LOCAL_CFLAGS := -flto -fdata-sections -ffunction-sections -Oz -fstack-protector-strong -D_FORTIFY_SOURCE=2 -mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4
+LOCAL_CFLAGS := -flto -fdata-sections -ffunction-sections -O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2 -mcpu=cortex-a7 -mfloat-abi=softfp -mfpu=neon-vfpv4
 LOCAL_CFLAGS += --target=arm-liteos --sysroot=$(LITEOSTOPDIR)/../../prebuilts/lite/sysroot/
 LOCAL_CFLAGS += -DMKSH_DISABLE_TTY_WARNING -DMKSH_SMALL=1 -DMKSH_ASSUME_UTF8=1 -DMKSH_SMALL_BUT_FAST=0 -DMKSH_S_NOVI=1 -DHAVE_CAN_FSTACKPROTECTORSTRONG=1
 LOCAL_CFLAGS += -DMKSH_LESS_CMDLINE_EDITING -DMKSH_LESS_BUILDINS -DMKSH_NO_INITCOMS -DADAPT_FOR_LITEOS_A