Refactor with image-only variable

Author: jpaquim

src/boot/boot.janet

@@ -4934,16 +4934,15 @@
      "src/core/wrap.c"])
 
   # Print janet.c to stdout
-  (if (has-value? boot/args "image-only")
-    (print "/* Image-only build - DO NOT EDIT */")
-    (print "/* Amalgamated build - DO NOT EDIT */"))
+  (def image-only (has-value? boot/args "image-only"))
+  (print "/* " (if image-only "Image-only" "Amalgamated") " build - DO NOT EDIT */")
   (print "/* Generated from janet version " janet/version "-" janet/build " */")
   (print "#define JANET_BUILD \"" janet/build "\"")
   (print ```#define JANET_AMALG```)
 
   (defn do-one-file
     [fname]
-    (unless (has-value? boot/args "image-only")
+    (unless image-only
       (print "\n/* " fname " */")
       (print "#line 0 \"" fname "\"\n")
       (def source (slurp fname))