change makefile to be more helpful for "seletc-startup.rkt" failure

racket/src/racket/Makefile.in

@@ -319,7 +319,7 @@ headers:
 # of the the other targets is selected by a recursive `$(MAKE)`.
 
 cstartup@STARTUP_AS_AUTO@:
-	$(MAKE) `@RUN_RACKET_CGC@ -cu $(srcdir)/src/startup-select.rkt`
+	$(MAKE) cstartup_`@RUN_RACKET_CGC@ -cu $(srcdir)/src/startup-select.rkt`
 
 # For compiling the startup code to bytecode
 cstartup@STARTUP_AS_BYTECODE@:
@@ -330,6 +330,10 @@ cstartup@STARTUP_AS_C@:
 	@RUN_RACKET_CGC@ -cu $(srcdir)/src/cify-check.rkt $(CSTARTUPDEST)
 	$(MAKE) cstartup.inc
 
+cstartup_:
+	echo "Bad startup choice, probably an error running startup-select.rkt"
+	exit 1
+
 # Running "cify-startup.rkt" through "$(SETUP_BOOT)" generates more
 # dependencies in "cstartup.d" for `$(CSTARTUPDEST)`
 $(CSTARTUPDEST): $(srcdir)/src/startup.inc $(srcdir)/src/schvers.h

racket/src/racket/src/startup-select.rkt

@@ -1,6 +1,6 @@
 (module startup-select '#%kernel
   (if (eval-jit-enabled)
-      (display "cstartup_bytecode")
-      (display "cstartup_c"))
+      (display "bytecode")
+      (display "c"))
   (newline))