Makefile: append branch name to EXENAME if not manually set

src/Makefile

@@ -183,6 +183,19 @@ include Makefile.d/detect.mk
 sources:=
 makedir:=../make
 
+exe:=ringracers
+
+# append branch name by default
+ifndef EXENAME
+branch:=$(shell git symbolic-ref -q --short HEAD)
+
+# not a detached HEAD
+ifdef branch
+exe:=$(exe)_$(branch)
+endif
+
+endif
+
 # -DCOMPVERSION: flag to use comptime.h
 opts:=-DCOMPVERSION -g
 libs:=
@@ -236,7 +249,7 @@ bin:=../bin
 endif
 
 # default EXENAME (usually set by platform)
-EXENAME?=ringracers
+EXENAME?=$(exe)
 DBGNAME?=$(EXENAME).debug
 
 exe:=$(bin)/$(EXENAME)

src/Makefile.d/win32.mk

@@ -2,11 +2,7 @@
 # Mingw, if you don't know, that's Win32/Win64
 #
 
-ifndef MINGW64
-EXENAME?=ringracers.exe
-else
-EXENAME?=ringracers64.exe
-endif
+exe:=$(exe)$(if $(MINGW64),64).exe
 
 # disable dynamicbase if under msys2
 ifdef MSYSTEM