Quick Compiler: pointer/boolean cleanup

More minor code cleanup - follow the Art convention of not treating
pointers as booleans in "for" loop tests.

Change-Id: I2fcd06efe6a51d1195c0900f7fa110fc01110001
diff --git a/src/compiler/ralloc.cc b/src/compiler/ralloc.cc
index 4f4d489..c2e663e 100644
--- a/src/compiler/ralloc.cc
+++ b/src/compiler/ralloc.cc
@@ -74,7 +74,7 @@
       bb->block_type != kExitBlock)
     return false;
 
-  for (MIR* mir = bb->first_mir_insn; mir; mir = mir->next) {
+  for (MIR* mir = bb->first_mir_insn; mir != NULL; mir = mir->next) {
     SSARepresentation *ssa_rep = mir->ssa_rep;
     if (ssa_rep) {
       for (int i = 0; i < ssa_rep->num_uses; i++) {
@@ -102,7 +102,7 @@
   if (bb->block_type != kDalvikByteCode && bb->block_type != kEntryBlock)
     return false;
 
-  for (mir = bb->first_mir_insn; mir; mir = mir->next) {
+  for (mir = bb->first_mir_insn; mir != NULL; mir = mir->next) {
     SSARepresentation *ssa_rep = mir->ssa_rep;
     if (ssa_rep) {
       int attrs = oat_data_flow_attributes[mir->dalvikInsn.opcode];