update usage info for Go 1.4+ (useless -data)

Because *.c files are not compiled anymore with Go 1.4+ toolchain, the
-data option in current shape has become useless. Usage info is changed
to reflect that.

Note: this could still possibly be done by generating *.s files, but
that'd be much more work. As of now, I don't have plans to do that.

README.txt

@@ -10,20 +10,12 @@ rsrc [-manifest FILE.exe.manifest] [-ico FILE.ico[,FILE2.ico...]] -o FILE.syso
   Icon embedded this way will show up on application's .exe instead of empty icon.
   Manifest file embedded this way will be recognized and detected by Windows.
 
-rsrc -data FILE.dat -o FILE.syso > FILE.c
-  Generates a .syso file with specified opaque binary blob embedded,
-  together with related .c file making it possible to access from Go code.
-  Theoretically cross-platform, but reportedly cannot compile together with cgo.
-
-The generated *.syso and *.c files should get automatically recognized
-by 'go build' command and linked into an executable/library, as long as
-there are any *.go files in the same directory.
-
-NOTE: starting with Go 1.4+, *.c files reportedly won't be linkable any more,
-      see: https://codereview.appspot.com/149720043
+The generated *.syso files should get automatically recognized by 'go build'
+command and linked into an executable/library, as long as there are any *.go
+files in the same directory.
 
 OPTIONS:
-  -data="": path to raw data file to embed
+  -data="": path to raw data file to embed [WARNING: useless for Go 1.4+]
   -ico="": comma-separated list of paths to .ico files to embed
   -manifest="": path to a Windows manifest file to embed
   -o="rsrc.syso": name of output COFF (.res or .syso) file

rsrc.go

@@ -42,14 +42,9 @@ var usage = `USAGE:
   Generates a .syso file with specified resources embedded in .rsrc section,
   aimed for consumption by Go linker when building Win32 excecutables.
 
-%s -data FILE.dat -o FILE.syso > FILE.c
-  Generates a .syso file with specified opaque binary blob embedded,
-  together with related .c file making it possible to access from Go code.
-  Theoretically cross-platform, but reportedly cannot compile together with cgo.
-
-The generated *.syso and *.c files should get automatically recognized
-by 'go build' command and linked into an executable/library, as long as
-there are any *.go files in the same directory.
+The generated *.syso files should get automatically recognized by 'go build'
+command and linked into an executable/library, as long as there are any *.go
+files in the same directory.
 
 OPTIONS:
 `
@@ -61,11 +56,11 @@ func main() {
 	flags := flag.NewFlagSet("", flag.ContinueOnError)
 	flags.StringVar(&fnamein, "manifest", "", "path to a Windows manifest file to embed")
 	flags.StringVar(&fnameico, "ico", "", "comma-separated list of paths to .ico files to embed")
-	flags.StringVar(&fnamedata, "data", "", "path to raw data file to embed")
+	flags.StringVar(&fnamedata, "data", "", "path to raw data file to embed [WARNING: useless for Go 1.4+]")
 	flags.StringVar(&fnameout, "o", "rsrc.syso", "name of output COFF (.res or .syso) file")
 	_ = flags.Parse(os.Args[1:])
 	if fnameout == "" || (fnamein == "" && fnamedata == "" && fnameico == "") {
-		fmt.Fprintf(os.Stderr, usage, os.Args[0], os.Args[0])
+		fmt.Fprintf(os.Stderr, usage, os.Args[0])
 		flags.PrintDefaults()
 		os.Exit(1)
 	}