Use characters instead of numeric constants to avoid the
gcc6 narrowing warning.

--- libk3b/tools/k3bwavefilewriter.cpp	2014-11-04 19:37:31.000000000 +0100
+++ libk3b/tools/k3bwavefilewriter.cpp	2016-09-22 18:26:13.443173213 +0200
@@ -111,17 +111,17 @@
 {
     static const char riffHeader[] =
         {
-            0x52, 0x49, 0x46, 0x46, // 0  "RIFF"
-            0x00, 0x00, 0x00, 0x00, // 4  wavSize
-            0x57, 0x41, 0x56, 0x45, // 8  "WAVE"
-            0x66, 0x6d, 0x74, 0x20, // 12 "fmt "
-            0x10, 0x00, 0x00, 0x00, // 16
-            0x01, 0x00, 0x02, 0x00, // 20
-            0x44, 0xac, 0x00, 0x00, // 24
-            0x10, 0xb1, 0x02, 0x00, // 28
-            0x04, 0x00, 0x10, 0x00, // 32
-            0x64, 0x61, 0x74, 0x61, // 36 "data"
-            0x00, 0x00, 0x00, 0x00  // 40 byteCount
+            '\x52', '\x49', '\x46', '\x46', // 0  "RIFF"
+            '\x00', '\x00', '\x00', '\x00', // 4  wavSize
+            '\x57', '\x41', '\x56', '\x45', // 8  "WAVE"
+            '\x66', '\x6d', '\x74', '\x20', // 12 "fmt "
+            '\x10', '\x00', '\x00', '\x00', // 16
+            '\x01', '\x00', '\x02', '\x00', // 20
+            '\x44', '\xac', '\x00', '\x00', // 24
+            '\x10', '\xb1', '\x02', '\x00', // 28
+            '\x04', '\x00', '\x10', '\x00', // 32
+            '\x64', '\x61', '\x74', '\x61', // 36 "data"
+            '\x00', '\x00', '\x00', '\x00'  // 40 byteCount
         };
 
     m_outputStream.writeRawData( riffHeader, 44 );
--- libk3b/projects/k3bcdrdaowriter.cpp	2014-11-04 19:37:31.000000000 +0100
+++ libk3b/projects/k3bcdrdaowriter.cpp	2016-09-22 18:30:15.231271203 +0200
@@ -908,7 +908,7 @@
 
 void K3b::CdrdaoWriter::parseCdrdaoMessage()
 {
-    static const char msgSync[] = { 0xff, 0x00, 0xff, 0x00 };
+    static const char msgSync[] = { '\xff', '\x00', '\xff', '\x00' };
     unsigned int avail = m_comSock->bytesAvailable();
     unsigned int msgs = avail / ( sizeof(msgSync)+d->progressMsgSize );
     unsigned int count = 0;
--- plugins/encoder/external/k3bexternalencoder.cpp	2014-11-04 19:37:31.000000000 +0100
+++ plugins/encoder/external/k3bexternalencoder.cpp	2016-09-22 18:33:15.300347286 +0200
@@ -39,17 +39,17 @@
 
 static const char s_riffHeader[] =
 {
-    0x52, 0x49, 0x46, 0x46, // 0  "RIFF"
-    0x00, 0x00, 0x00, 0x00, // 4  wavSize
-    0x57, 0x41, 0x56, 0x45, // 8  "WAVE"
-    0x66, 0x6d, 0x74, 0x20, // 12 "fmt "
-    0x10, 0x00, 0x00, 0x00, // 16
-    0x01, 0x00, 0x02, 0x00, // 20
-    0x44, 0xac, 0x00, 0x00, // 24
-    0x10, 0xb1, 0x02, 0x00, // 28
-    0x04, 0x00, 0x10, 0x00, // 32
-    0x64, 0x61, 0x74, 0x61, // 36 "data"
-    0x00, 0x00, 0x00, 0x00  // 40 byteCount
+    '\x52', '\x49', '\x46', '\x46', // 0  "RIFF"
+    '\x00', '\x00', '\x00', '\x00', // 4  wavSize
+    '\x57', '\x41', '\x56', '\x45', // 8  "WAVE"
+    '\x66', '\x6d', '\x74', '\x20', // 12 "fmt "
+    '\x10', '\x00', '\x00', '\x00', // 16
+    '\x01', '\x00', '\x02', '\x00', // 20
+    '\x44', '\xac', '\x00', '\x00', // 24
+    '\x10', '\xb1', '\x02', '\x00', // 28
+    '\x04', '\x00', '\x10', '\x00', // 32
+    '\x64', '\x61', '\x74', '\x61', // 36 "data"
+    '\x00', '\x00', '\x00', '\x00'  // 40 byteCount
 };