Fix warnings and a C++ error.

Fix warnings and a C++ error.

mono/master 32beba680eda59a95894713388116cf904eaf453 with no local edits

The C++ compilation was likely an accident and I'll try again after git clean.

jaymac1:mono jay$ cat sdks/Mak*g
ENABLE_CXX=1

will run again with git clean.

 make -C sdks/builds build-ios-cross32 build-android-cross-arm build-android-cross-x86

/s/mono/mono/mini/mini-llvm.c:7729:18: warning: unused variable 'iter' [-Wunused-variable]
                GHashTableIter iter;
                               ^
/s/mono/mono/mini/mini-llvm.c:7730:15: warning: unused variable 'method' [-Wunused-variable]
                MonoMethod *method;
                            ^
/s/mono/mono/mini/mini-llvm.c:7731:11: warning: unused variable 'callers' [-Wunused-variable]
                GSList *callers, *l, *l2;
                        ^
/s/mono/mono/mini/mini-llvm.c:7731:21: warning: unused variable 'l' [-Wunused-variable]
                GSList *callers, *l, *l2;
                                  ^
/s/mono/mono/mini/mini-llvm.c:7731:25: warning: unused variable 'l2' [-Wunused-variable]
                GSList *callers, *l, *l2;
                                      ^
/s/mono/mono/mini/mini-llvm.c:9022:13: error: cannot initialize a variable of type 'CallSite *' with an lvalue of type 'gpointer' (aka 'void *')
                CallSite *site = g_ptr_array_index (module->callsite_list, sindex);
                          ^      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/s/mono/mono/mini/mini-llvm.c:9002:17: warning: unused variable 'iter' [-Wunused-variable]
        GHashTableIter iter;
                       ^
/s/mono/mono/mini/mini-llvm.c:9004:10: warning: unused variable 'callers' [-Wunused-variable]
        GSList *callers, *l;
                ^
/s/mono/mono/mini/mini-llvm.c:9004:20: warning: unused variable 'l' [-Wunused-variable]
        GSList *callers, *l;