add openssl hmac

delete GetMD and HMAC function

delete macro

tidy code

add hmac

c/openssl/_demo/chmacdemo/hmac.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"unsafe"
+
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/c/openssl"
+)
+
+func main() {
+	str := "Hello, World!"
+	key := "123456"
+	var lenKey = len(key)
+
+	var digest = make([]byte, openssl.EVP_MAX_MD_SIZE)
+	var digestLen c.Uint
+	ctx := openssl.NewHMAC_CTX()
+	if ctx == nil {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error creating HMAC_CTX"))
+		return
+	}
+	defer ctx.Free()
+
+	var ret c.Int = ctx.InitEx(unsafe.Pointer(unsafe.StringData(key)), c.Int(lenKey), openssl.EVP_sha256(), nil)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error initializing HMAC_CTX"))
+		return
+	}
+	ret = ctx.UpdateString(str)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error updating HMAC_CTX"))
+		return
+	}
+	ret = ctx.Final(unsafe.SliceData(digest), &digestLen)
+	if ret == 0 {
+		c.Fprintf(c.Stderr, c.Str("%s\n"), c.Str("Error finalizing HMAC_CTX"))
+		return
+	}
+	fmt.Print("HMAC: ")
+	for i := 0; i < int(digestLen); i++ {
+		fmt.Printf("%02x", digest[i])
+	}
+	fmt.Print("\n")
+}