Fixes 2 kinds of warnings.

1) The last parameter of getGetElementPtr() has type bool. In some instances, a 2 is used as parameter. This is converted to true.
2) Several loops use int instead of unsigned. This causes warning about signed/unsigned mismatch.

Curiously, only Visual C++ complains about this. Nevertheless I think that the warnings should be fixed.

gen/asmstmt.cpp

@@ -534,7 +534,7 @@ void AsmBlockStatement::toIR(IRState* p)
     p->asmBlock = asmblock;
 
     // do asm statements
-    for (int i=0; i<statements->dim; i++)
+    for (unsigned i=0; i<statements->dim; i++)
     {
         Statement* s = (Statement*)statements->data[i];
         if (s) {