Allow for variables in pack to be unused

This fixes a whole bunch of warnings on the clang analyzer, so actual
issues aren't swamped in the dead store warnings it throws. This also
means all code in the vm/ directory (except for util) now is clean with
the analyzer.

vm/builtin/pack18.cpp

@@ -632,11 +632,11 @@ namespace rubinius {
 
     native_int array_size = self->size();
     native_int index = 0;
-    native_int count = 0;
+    native_int count UNUSED = 0;
     native_int stop = 0;
-    bool rest = false;
-    bool platform = false;
-    bool tainted = false;
+    bool rest UNUSED = false;
+    bool platform UNUSED = false;
+    bool tainted UNUSED  = false;
 
     String* string_value = 0;
     std::string str("");

vm/builtin/pack19.cpp

@@ -637,12 +637,12 @@ namespace rubinius {
 
     native_int array_size = self->size();
     native_int index = 0;
-    native_int count = 0;
+    native_int count UNUSED = 0;
     native_int count_flag = -1;
     native_int stop = 0;
-    bool rest = false;
-    bool tainted = false;
-    bool untrusted = false;
+    bool rest UNUSED = false;
+    bool tainted UNUSED = false;
+    bool untrusted UNUSED = false;
     bool ascii_encoding = false;
     bool utf8_encoding = false;
     bool string_encoding = false;

vm/builtin/unpack18.cpp

@@ -167,9 +167,9 @@ namespace rubinius {
 
       int a = -1, b = -1, c = 0, d = 0;
       while(bytes < bytes_end) {
-        a = b = c = d = -1;
+        b = c = d = -1;
 
-        while((a = b64_xtable[(int)(*bytes)]) == -1 && bytes < bytes_end)
+        while((a = (int)b64_xtable[(int)(*bytes)]) == -1 && bytes < bytes_end)
           bytes++;
         if(bytes >= bytes_end)
           break;
@@ -627,13 +627,13 @@ namespace rubinius {
     const char* bytes_end = 0;
 
     native_int bytes_size = self->byte_size();
-    native_int index = 0;
+    native_int index UNUSED = 0;
     native_int stop = 0;
     native_int width = 0;
-    native_int count = 0;
+    native_int count UNUSED = 0;
     native_int remainder = 0;
-    bool rest = false;
-    bool platform = false;
+    bool rest UNUSED = false;
+    bool platform UNUSED = false;
 
 
 static const char _trans_keys[] = {

vm/builtin/unpack19.cpp

@@ -172,9 +172,9 @@ namespace rubinius {
 
       int a = -1, b = -1, c = 0, d = 0;
       while(bytes < bytes_end) {
-        a = b = c = d = -1;
+        b = c = d = -1;
 
-        while((a = b64_xtable[(int)(*bytes)]) == -1 && bytes < bytes_end)
+        while((a = (int)b64_xtable[(int)(*bytes)]) == -1 && bytes < bytes_end)
           bytes++;
         if(bytes >= bytes_end)
           break;
@@ -632,12 +632,12 @@ namespace rubinius {
     const char* bytes_end = 0;
 
     native_int bytes_size = self->byte_size();
-    native_int index = 0;
+    native_int index UNUSED = 0;
     native_int stop = 0;
     native_int width = 0;
-    native_int count = 0;
+    native_int count UNUSED = 0;
     native_int remainder = 0;
-    bool rest = false;
+    bool rest UNUSED = false;
 
 
 static const char _trans_keys[] = {

vm/prelude.hpp

@@ -41,8 +41,10 @@ namespace rubinius {
 
 #if __GNUC__ >= 4
 #define WARN_UNUSED __attribute__ ((warn_unused_result))
+#define UNUSED __attribute__((unused))
 #else
 #define WARN_UNUSED
+#define UNUSED
 #endif
 
 #endif