Fix unix/Makefile to build on OSX

Force OSX to compile with clang even if gcc is available
Change LDFLAGS syntax to be compatible with clang
Fix questionable syntax on line 90
Remove extraneous tab character

unix/Makefile

@@ -30,6 +30,13 @@ COPT = -Os #-DNDEBUG
 endif
 
 LDFLAGS = $(LDFLAGS_MOD) -lm -Wl,-Map=$@.map,--cref $(LDFLAGS_EXTRA)
+ifeq ($(UNAME_S),Darwin)
+# Force OSX to use clang even if gcc is present, value set in mkenv.mk
+# must be ovewritten here to avoid breaking stmhal build on OSX
+CC = clang
+# Use clang syntax for LDFLAGS
+LDFLAGS = $(LDFLAGS_MOD) -lm -Wl,-map,$@.map $(LDFLAGS_EXTRA)
+endif
 
 ifeq ($(MICROPY_FORCE_32BIT),1)
 CFLAGS += -m32
@@ -80,7 +87,7 @@ SRC_C = \
 
 ifeq ($(UNAME_S),Darwin)
 
-LDFLAGS+ = -Wl,-order_file,$(BUILD)/order.def
+LDFLAGS += -Wl,-order_file,$(BUILD)/order.def
 
 # Must be the last file in list of sources
 SRC_C += seg_helpers.c
@@ -92,7 +99,7 @@ seg_helpers.c: $(BUILD)/order.def
 $(BUILD)/order.def:
 	$(Q)echo "seg_helpers.o: ___bss_start" > $@
 endif
-	
+
 OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 include ../py/mkrules.mk