Rename HB_TAG_STR() to HB_TAG_CHAR4()

The problem with HB_TAG_STR() was that it expected a string of size 4
exactly, and unlike hb_tag_from_string() it doesn't pad the tag with
space characters.  So, the new name is more appropriate.

src/hb-common.c

@@ -40,7 +40,7 @@ hb_tag_from_string (const char *s)
   for (; i < 4; i++)
     tag[i] = ' ';
 
-  return HB_TAG_STR (tag);
+  return HB_TAG_CHAR4 (tag);
 }
 
 

src/hb-common.h

@@ -55,10 +55,10 @@ typedef int hb_bool_t;
 
 typedef uint32_t hb_tag_t;
 #define HB_TAG(a,b,c,d) ((hb_tag_t)((((uint8_t)(a))<<24)|(((uint8_t)(b))<<16)|(((uint8_t)(c))<<8)|((uint8_t)(d))))
-#define HB_TAG_STR(s)   (HB_TAG(((const char *) s)[0], \
-				((const char *) s)[1], \
-				((const char *) s)[2], \
-				((const char *) s)[3]))
+#define HB_TAG_CHAR4(s)   (HB_TAG(((const char *) s)[0], \
+				  ((const char *) s)[1], \
+				  ((const char *) s)[2], \
+				  ((const char *) s)[3]))
 #define HB_TAG_NONE HB_TAG(0,0,0,0)
 
 hb_tag_t hb_tag_from_string (const char *s);

src/hb-ot-tag.c

@@ -645,7 +645,7 @@ hb_ot_tag_from_language (hb_language_t language)
       tag[i] = TO_UPPER (lang_str[i]);
     for (; i < 4; i++)
       tag[i] = ' ';
-    return HB_TAG_STR (tag);
+    return HB_TAG_CHAR4 (tag);
   }
 
   /* find a language matching in the first component */

test/test-types.c

@@ -85,7 +85,7 @@ test_types_tag (void)
   g_assert_cmphex (HB_TAG_NONE, ==, 0);
   g_assert_cmphex (HB_TAG ('a','B','c','D'), ==, 0x61426344);
 
-  g_assert_cmphex (HB_TAG_STR ("aBcD"), ==, 0x61426344);
+  g_assert_cmphex (HB_TAG_CHAR4 ("aBcD"), ==, 0x61426344);
 
   g_assert_cmphex (hb_tag_from_string ("aBcDe"), ==, 0x61426344);
   g_assert_cmphex (hb_tag_from_string ("aBcD"),  ==, 0x61426344);