configure: option to disable reflector

The option will likely not be used alone but rather implicitly by
--disable-all and it can be used to speed-up the compilation if reflector
is not needed (and maybe also if its compilation is failing).

Makefile.in

@@ -52,7 +52,9 @@ SYSTEM	      = @system@
 GUI_EXE      ?= @GUI_EXE@
 GUI_TARGET    = @GUI_TARGET@
 QT_CFLAGS     = @QT_CFLAGS@
-REFLECTOR_TARGET ?= bin/hd-rum-transcode$(EXEEXT)
+ifeq ($(origin REFLECTOR_TARGET), undefined)
+REFLECTOR_TARGET = @REFLECTOR_TARGET@$(EXEEXT)
+endif
 TEST_TARGET  = bin/run_tests$(EXEEXT)
 
 PACKAGE_TARNAME ?= @PACKAGE_TARNAME@

configure.ac

@@ -3245,6 +3245,19 @@ fi
 
 ENSURE_FEATURE_PRESENT([$sdl_mixer_req], [$sdl_mixer], [SDL_mixer deps not found!])
 
+# -----------------------------------------------------------------------------
+# Reflector
+# -----------------------------------------------------------------------------
+AC_ARG_ENABLE(reflector,
+              AS_HELP_STRING([--disable-reflector], [disables reflector (default is enabled)]),
+              [reflector_req=$enableval],
+              [reflector_req=$build_default])
+REFLECTOR_TARGET=
+if test "$reflector_req" != no; then
+        REFLECTOR_TARGET=bin/hd-rum-transcode
+fi
+AC_SUBST(REFLECTOR_TARGET)
+
 # -------------------------------------------------------------------------------------------------
 # We need to add libraries then
 # -------------------------------------------------------------------------------------------------