account for different M1 vs x86_64 brew prefixes

compile.sh

@@ -103,7 +103,12 @@ if [ "$(uname -s)" == "Darwin" ]; then
 	type glibtool >> "$DIR/install.log" 2>&1 || { write_error "Please install 'libtool' using Homebrew."; ((ERRORS++)); }
 	export LIBTOOL=glibtool
 	export LIBTOOLIZE=glibtoolize
-	export PATH="/opt/homebrew/opt/bison/bin:/opt/homebrew/opt/llvm/bin:$PATH"
+	if [ "$(uname -m)" == "arm64" ]; then
+		brew_prefix="/opt/homebrew"
+	else
+		brew_prefix="/usr/local"
+	fi
+	export PATH="$brew_prefix/opt/bison/bin:$brew_prefix/opt/llvm/bin:$PATH"
 	[[ $(clang --version) == "Apple clang"* ]] && { write_error "MacOS bundled clang is broken. Install 'llvm' using Homebrew."; ((ERRORS++)); }
 	[[ $(bison --version) == "bison (GNU Bison) 3."* ]] || { write_error "MacOS bundled bison is too old. Install 'bison' using Homebrew."; ((ERRORS++)); }