Use `gcc -E` for `cpp` (#1639)

* Fix cpp for macs?

* Add comment

* Move cppflags with cpp

Makefile

@@ -87,12 +87,6 @@ BASEROM_DIR   := baseroms/$(VERSION)
 BUILD_DIR     := build/$(VERSION)
 EXTRACTED_DIR := extracted/$(VERSION)
 
-CPPFLAGS += -P
-
-ifeq ($(DETECTED_OS), macos)
-  CPPFLAGS += -xc++
-endif
-
 
 #### Tools ####
 ifneq ($(shell type $(MIPS_BINUTILS_PREFIX)ld >/dev/null 2>/dev/null; echo $$?), 0)
@@ -143,7 +137,11 @@ ifeq ($(RUN_CC_CHECK),0)
   CC_CHECK_COMP    := @:
 endif
 
-CPP           := cpp
+# The `cpp` command behaves differently on macOS (it behaves as if
+# `-traditional-cpp` was passed) so we use `gcc -E` instead.
+CPP           := gcc -E
+CPPFLAGS      += -P -xc -fno-dollars-in-identifiers
+
 MKLDSCRIPT    := tools/buildtools/mkldscript
 MKDMADATA     := tools/buildtools/mkdmadata
 ZAPD          := tools/ZAPD/ZAPD.out

tools/disasm/disasm.py

@@ -1097,10 +1097,10 @@ def find_symbols_in_rodata(section):
 def asm_header(section_name: str):
     return f""".include "macro.inc"
 
-# assembler directives
-.set noat      # allow manual use of $at
-.set noreorder # don't insert nops after branches
-.set gp=64     # allow use of 64-bit general purpose registers
+/* assembler directives */
+.set noat      /* allow manual use of $at */
+.set noreorder /* don't insert nops after branches */
+.set gp=64     /* allow use of 64-bit general purpose registers */
 
 .section {section_name}