Add __clear_cache implementation in libtcc1

Add __clear_cache function for flushing caches to libtcc1.

lib/Makefile

@@ -24,6 +24,10 @@ ifndef TARGET
   ifneq ($(TARGETOS),Darwin)
    XCC = $(CC)
   endif
+ else
+ ifeq ($(ARCH),arm)
+  TARGET = arm
+ endif
  endif
  endif
  endif
@@ -41,6 +45,7 @@ cross : TCC = $(TOP)/$(TARGET)-tcc$(EXESUF)
 
 I386_O = libtcc1.o alloca86.o alloca86-bt.o $(BCHECK_O)
 X86_64_O = libtcc1.o alloca86_64.o
+ARM_O = libtcc1.o
 WIN32_O = $(I386_O) crt1.o wincrt1.o dllcrt1.o dllmain.o chkstk.o
 WIN64_O = $(X86_64_O) crt1.o wincrt1.o dllcrt1.o dllmain.o chkstk.o
 
@@ -65,12 +70,18 @@ ifeq "$(TARGET)" "x86_64"
  OBJ = $(addprefix $(DIR)/,$(X86_64_O))
  TGT = -DTCC_TARGET_X86_64
  XCC ?= $(TCC) -B$(TOP)
+else
+ifeq "$(TARGET)" "arm"
+ OBJ = $(addprefix $(DIR)/,$(ARM_O))
+ TGT = -DTCC_TARGET_ARM
+ XCC ?= $(TCC) -B$(TOP)
 else
  $(error libtcc1.a not supported on target '$(TARGET)')
 endif
 endif
 endif
 endif
+endif
 
 XFLAGS = $(CPPFLAGS) $(CFLAGS) $(TGT)