include: cleanup for -Wsystem-header

- warnings as errors, or errors introduced when -Wsystem-header
  was experimentally introduced.

Change-Id: Ia8f5b3c1c1096e191741223d52526aa48c7f1cc4
diff --git a/include/cutils/bitops.h b/include/cutils/bitops.h
index c26dc54..045830d 100644
--- a/include/cutils/bitops.h
+++ b/include/cutils/bitops.h
@@ -59,7 +59,7 @@
 static inline int bitmask_ffz(unsigned int *bitmask, int num_bits)
 {
     int bit, result;
-    unsigned int i;
+    size_t i;
 
     for (i = 0; i < BITS_TO_WORDS(num_bits); i++) {
         bit = ffs(~bitmask[i]);
@@ -77,7 +77,7 @@
 
 static inline int bitmask_weight(unsigned int *bitmask, int num_bits)
 {
-    int i;
+    size_t i;
     int weight = 0;
 
     for (i = 0; i < BITS_TO_WORDS(num_bits); i++)