port: allow overriding CC and CXX

Makefile.port

@@ -151,9 +151,15 @@ G_DIR := src/generated/$(ROMID)
 
 ifneq (,$(findstring windows,$(TARGET_PLATFORM)))
   TARGET_CFLAGS := $(shell pkg-config sdl2 --cflags-only-I)
-  TARGET_LDFLAGS := $(shell pkg-config sdl2 --libs) -lz -lopengl32 -static-libstdc++ -ldbghelp
+  TARGET_LDFLAGS := $(shell pkg-config sdl2 --libs) -lz -lopengl32 -ldbghelp
   # on windows/mingw we need this to be built with a 32-bit compiler so it finds the correct libs
   TOOLCHAIN ?= i686-w64-mingw32-
+  # on GCC link libstdc++ statically
+  ifeq (,$(findstring clang,$(CC))$(findstring clang,$(CXX)))
+    TARGET_LDFLAGS += -static-libstdc++
+  else
+    TARGET_LDFLAGS += -lstdc++
+  endif
 else # assume *nix
   TARGET_CFLAGS := $(shell pkg-config sdl2 --cflags-only-I)
   TARGET_LDFLAGS := $(shell pkg-config sdl2 --libs) -lGL -lz -ldl
@@ -162,6 +168,10 @@ else # assume *nix
     # TODO: detect soft/hardfloat abi
     TOOLCHAIN ?= arm-linux-gnueabihf-
   endif
+  # on clang link libc++
+  ifneq (,$(findstring clang,$(CC))$(findstring clang,$(CXX)))
+    TARGET_LDFLAGS += -lc++
+  endif
 endif
 
 # On x86_64 gcc add -m32 to CFLAGS if building a 32-bit executable.
@@ -233,8 +243,8 @@ INCLUDES = \
   -I port/include
 
 TOOLCHAIN ?=
-CC := $(TOOLCHAIN)gcc -std=c11
-CXX := $(TOOLCHAIN)g++ -std=c++20
+CC ?= $(TOOLCHAIN)gcc
+CXX ?= $(TOOLCHAIN)g++
 ifneq (,$(CXX_O_FILES))
   LD := $(CXX)
 else
@@ -250,7 +260,6 @@ COMMON_CFLAGS := $(C_DEFINES) -DAVOID_UB=1 $(INCLUDES) $(TARGET_CFLAGS) -g \
   -fwrapv \
   -Wall \
   -Wno-address \
-  -Wno-aggressive-loop-optimizations \
   -Wno-int-in-bool-context \
   -Wno-misleading-indentation \
   -Wno-missing-braces \
@@ -261,8 +270,8 @@ COMMON_CFLAGS := $(C_DEFINES) -DAVOID_UB=1 $(INCLUDES) $(TARGET_CFLAGS) -g \
   -Wno-unused-variable \
   -Wno-format-truncation
 
-CFLAGS := $(COMMON_CFLAGS) -Wno-pointer-sign
-CXXFLAGS := $(COMMON_CFLAGS) -Wno-unused-function
+CFLAGS := -std=c11 $(COMMON_CFLAGS) -Wno-pointer-sign
+CXXFLAGS := -std=c++20 $(COMMON_CFLAGS) -Wno-unused-function
 LDFLAGS := $(TARGET_LDFLAGS)
 
 # Make ROMID available as an environment variable to all tooling.