Merge pull request #5830 from jcowgill/makefile-indentation

makefile.tmpl: fix error handling and cleanups

tools/niminst/makefile.tmpl

@@ -65,8 +65,7 @@ ifeq ($(uos),haiku)
   myos = haiku
 endif
 ifndef uos
-	@echo "Error: unknown operating system: $(uos)"
-	@exit 1
+  $(error unknown operating system: $(uos))
 endif
 
 ifeq ($(ucpu),i386)
@@ -131,8 +130,7 @@ ifeq ($(ucpu),armv6l)
   mycpu = arm
 endif
 ifndef ucpu
-	@echo "Error: unknown processor : $(ucpu)"
-	@exit 1
+  $(error unknown processor : $(ucpu))
 endif
 
 # for osA in 1..c.oses.len:
@@ -150,8 +148,7 @@ endif
 # end for
 
 ifeq ($(strip $(oFiles)),)
-	@echo "Error: no C code generated for: [$(myos): $(mycpu)]"
-	@exit 1
+  $(error no C code generated for: [$(myos): $(mycpu)])
 endif
 
 %.o: %.c