[Makefiles] Drop %.asm rule

%.asm is not widely used in unix world and the rule seems hacky.
So drop %.asm rule.

LibOS/shim/src/Makefile

@@ -97,12 +97,6 @@ else
 $(shim_target):
 endif
 
-%.asm: %.c $(headers)
-	@echo [ $@ ]
-	@$(CC) $(CFLAGS) $(defs) -c $< -o $<.o
-	@objdump -S $<.o > $@
-	@rm $<.o
-
 $(addsuffix .o,$(addprefix ipc/shim_ipc_,$(ipcns))): $(wildcard ipc/*.h)
 elf/shim_rtld.o: $(wildcard elf/*.h)
 

Pal/src/Makefile

@@ -134,13 +134,6 @@ $(pal_static): $(addprefix $(OBJ_DIR)/,$(addsuffix .o,$(objs))) \
 	       $(host_lib) $(graphene_lib)
 	$(call cmd,ar_a_o)
 
-$(OBJ_DIR)/%.asm: %.c $(headers)
-	@mkdir -p $(OBJ_DIR)
-	@echo [ $@ ]
-	@$(CC) $(CFLAGS) $(defs) -c $< -o $<.o
-	@objdump -S $<.o > $@
-	@rm $<.o
-
 user_start.o: ASFLAGS =
 user_start.o: user_start.S
 	$(call cmd,as_o_S)

Pal/src/host/FreeBSD/Makefile

@@ -32,11 +32,6 @@ pal-gdb: pal-gdb.template
 libpal-FreeBSD.a: $(addsuffix .o,$(objs)) $(graphene_lib)
 	$(call cmd,ar_a_o)
 
-%.asm: %.c $(headers)
-	$(CC) $(CFLAGS) $(defs) -c $< -o $<.o
-	@objdump -S $<.o > $@
-	@rm $<.o
-
 %.o: %.c $(headers)
 	$(call cmd,cc_o_c)
 

Pal/src/host/Linux/Makefile

@@ -33,11 +33,6 @@ endif
 libpal-Linux.a: $(addsuffix .o,$(objs)) $(graphene_lib)
 	$(call cmd,ar_a_o)
 
-%.asm: %.c $(headers)
-	$(CC) $(CFLAGS) $(defs) -c $< -o $<.o
-	@objdump -S $<.o > $@
-	@rm $<.o
-
 %.o: %.c $(headers)
 	$(call cmd,cc_o_c)
 

Pal/src/host/Skeleton/Makefile

@@ -29,11 +29,6 @@ endif
 libpal-Skeleton.a: $(addsuffix .o,$(objs)) $(graphene_lib)
 	$(call cmd,ar_a_o)
 
-%.asm: %.c $(headers)
-	$(CC) $(CFLAGS) $(defs) -c $< -o $<.o
-	@objdump -S $<.o > $@
-	@rm $<.o
-
 %.o: %.c $(headers)
 	$(call cmd,cc_o_c)