util/StringUtil: add ToUpperASCII()

Replaces g_ascii_strup() and allows building the Vorbis encoder
without GLib.

src/util/StringUtil.cxx

@@ -120,3 +120,23 @@ string_array_contains(const char *const* haystack, const char *needle)
 
 	return false;
 }
+
+void
+ToUpperASCII(char *dest, const char *src, size_t size)
+{
+	assert(dest != nullptr);
+	assert(src != nullptr);
+	assert(size > 1);
+
+	char *const end = dest + size - 1;
+
+	do {
+		char ch = *src++;
+		if (ch == 0)
+			break;
+
+		*dest++ = ToUpperASCII(ch);
+	} while (dest < end);
+
+	*dest = 0;
+}

src/util/StringUtil.hxx

@@ -114,4 +114,12 @@ gcc_pure
 bool
 string_array_contains(const char *const* haystack, const char *needle);
 
+/**
+ * Convert the specified ASCII string (0x00..0x7f) to upper case.
+ *
+ * @param size the destination buffer size
+ */
+void
+ToUpperASCII(char *dest, const char *src, size_t size);
+
 #endif