Work around an issue where the order of flags matters on old nasm

Author: mintsuki

GNUmakefile

@@ -107,8 +107,9 @@ ifeq ($(ARCH),ia32)
         -mno-mmx
     override LDFLAGS += \
         -m elf_i386
-    override NASMFLAGS += \
-        -f elf32
+    override NASMFLAGS := \
+        -f elf32 \
+        $(NASMFLAGS)
 endif
 ifeq ($(ARCH),x86_64)
     ifeq ($(CC_IS_CLANG),1)
@@ -125,8 +126,9 @@ ifeq ($(ARCH),x86_64)
         -mno-red-zone
     override LDFLAGS += \
         -m elf_x86_64
-    override NASMFLAGS += \
-        -f elf64
+    override NASMFLAGS := \
+        -f elf64 \
+        $(NASMFLAGS)
 endif
 
 # Internal linker flags that should not be changed by the user.