Add the name of the forEach functions to the tracing output

Instead of showing up as 'runForEach', kernels are now e.g. printed as
'runForEach_createAntLookup'.

The String8 is carefully constructed here, such that we only pay
the string processing overhead in case tracing is actually enabled.

Change-Id: Id18319e271a02cbe888bcb9fe806794007d00fca
diff --git a/rsScript.h b/rsScript.h
index a1360b5..c868aaa 100644
--- a/rsScript.h
+++ b/rsScript.h
@@ -19,6 +19,7 @@
 
 #include "rsAllocation.h"
 
+#include <utility>
 
 // ---------------------------------------------------------------------------
 namespace android {
@@ -72,6 +73,7 @@
             size_t exportedPragmaCount;
             char const **exportedPragmaKeyList;
             char const **exportedPragmaValueList;
+            const std::pair<const char *, uint32_t> *exportedForeachFuncList;
 
             int (* root)();
         };