vendor/box2d: clarify wasm building

vendor/box2d/box2d.odin

@@ -24,7 +24,7 @@ when ODIN_OS == .Windows {
 }
 
 when !#exists(LIB_PATH) {
-	#panic("Could not find the compiled box2d libraries at \"" + LIB_PATH + "\", they can be compiled by running the `build.sh` script at `" + ODIN_ROOT + "vendor/box2d/build_box2d.sh\"`")
+	#panic("Could not find the compiled box2d libraries at \"" + LIB_PATH + "\", they can be compiled by running the `build_box2d.sh` script at `" + ODIN_ROOT + "vendor/box2d/build_box2d.sh\"`")
 }
 
 foreign import lib {

vendor/box2d/build_box2d.sh

@@ -68,7 +68,12 @@ esac
 
 cd ..
 
+set +e
 make -f wasm.Makefile
+if [[ $? -ne 0 ]]; then
+	printf "\e[30;43mwarning:\e[0m Native Box2D libraries were built successfully, the WASM build failed, likely because your default C compiler and/or linker doesn't support WASM, you can set the CC and LD environment variables to point to a compiler and linker that support it\n"
+fi
+set -e
 
 rm -rf v3.0.0.tar.gz
 rm -rf box2d-3.0.0

vendor/box2d/wasm.Makefile

@@ -2,6 +2,8 @@
 # I tried to make a cmake toolchain file for this / use cmake but this is far easier.
 # NOTE: We are pretending to be emscripten to box2d so it takes WASM code paths, but we don't actually use emscripten.
 
+# WARN: wasm is probably not supported by your default C compiler and linker, overwrite the CC and LD environment variables accordingly.
+# Example for MacOS:
 # CC = $(shell brew --prefix llvm)/bin/clang
 # LD = $(shell brew --prefix llvm)/bin/wasm-ld