rust_debug: Cast size_t values to unsigned long before printing.

Using %lu to format size_t values breaks 32 bit targets, and %zu is not
supported by one of the hosts GCC aims to support - HPUX

gcc/rust/ChangeLog:

	* backend/rust-compile-base.cc (HIRCompileBase::resolve_method_address):
	Cast size_t value to unsigned long.
	* expand/rust-proc-macro.cc (load_macros): Likewise.
	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::visit): Likewise.

gcc/rust/backend/rust-compile-base.cc

@@ -918,7 +918,8 @@ HIRCompileBase::resolve_method_address (TyTy::FnType *fntype,
     }
 
   const Resolver::PathProbeCandidate *selectedCandidate = nullptr;
-  rust_debug_loc (expr_locus, "resolved to %lu candidates", candidates.size ());
+  rust_debug_loc (expr_locus, "resolved to %lu candidates",
+		  (unsigned long) candidates.size ());
 
   // filter for the possible case of non fn type items
   std::set<Resolver::PathProbeCandidate> filteredFunctionCandidates;

gcc/rust/expand/rust-proc-macro.cc

@@ -171,7 +171,7 @@ load_macros (std::string path)
   if (array == nullptr)
     return {};
 
-  rust_debug ("Found %lu procedural macros", array->length);
+  rust_debug ("Found %lu procedural macros", (unsigned long) array->length);
 
   return std::vector<ProcMacro::Procmacro> (array->macros,
 					    array->macros + array->length);

gcc/rust/typecheck/rust-hir-type-check-expr.cc

@@ -1122,10 +1122,10 @@ TypeCheckExpr::visit (HIR::MethodCallExpr &expr)
 
   auto candidate = *candidates.begin ();
   rust_debug_loc (expr.get_method_name ().get_locus (),
-		  "resolved method to: {%u} {%s} with [%zu] adjustments",
+		  "resolved method to: {%u} {%s} with [%lu] adjustments",
 		  candidate.candidate.ty->get_ref (),
 		  candidate.candidate.ty->debug_str ().c_str (),
-		  candidate.adjustments.size ());
+		  (unsigned long) candidate.adjustments.size ());
 
   // Get the adjusted self
   Adjuster adj (receiver_tyty);