Use int32 for parameter block sizes.

CostFunction now uses int32 instead of int16
to store the size of its parameter blocks.

This is an API breaking change.

Change-Id: I032ea583bc7ea4b3009be25d23a3be143749c73e
diff --git a/internal/ceres/residual_block_test.cc b/internal/ceres/residual_block_test.cc
index 1e03e7d..b37f50f 100644
--- a/internal/ceres/residual_block_test.cc
+++ b/internal/ceres/residual_block_test.cc
@@ -43,9 +43,9 @@
 class TernaryCostFunction: public CostFunction {
  public:
   TernaryCostFunction(int num_residuals,
-                      int16 parameter_block1_size,
-                      int16 parameter_block2_size,
-                      int16 parameter_block3_size) {
+                      int32 parameter_block1_size,
+                      int32 parameter_block2_size,
+                      int32 parameter_block3_size) {
     set_num_residuals(num_residuals);
     mutable_parameter_block_sizes()->push_back(parameter_block1_size);
     mutable_parameter_block_sizes()->push_back(parameter_block2_size);