doc: Improve QByteArray::fromRawData snippet

The current snippet uses integer literals that will trigger the
Wnarrowing warning with recent version of gcc. This patch replaces them
with character literals to fix this warning.

Change-Id: Iffad495f24cc9d4c1674a7fe3f6b45c46a625ff8
Reviewed-by: Sze Howe Koh <szehowe.koh@gmail.com>

src/corelib/doc/snippets/code/src_corelib_tools_qbytearray.cpp

@@ -395,10 +395,10 @@ QByteArray ba = QByteArray::number(12.3456, 'E', 3);
 
 //! [43]
  static const char mydata[] = {
-    0x00, 0x00, 0x03, 0x84, 0x78, 0x9c, 0x3b, 0x76,
-    0xec, 0x18, 0xc3, 0x31, 0x0a, 0xf1, 0xcc, 0x99,
+    '\x00', '\x00', '\x03', '\x84', '\x78', '\x9c', '\x3b', '\x76',
+    '\xec', '\x18', '\xc3', '\x31', '\x0a', '\xf1', '\xcc', '\x99',
     ...
-    0x6d, 0x5b
+    '\x6d', '\x5b'
 };
 
 QByteArray data = QByteArray::fromRawData(mydata, sizeof(mydata));