Using int64 in file.cc. Fixing compilation error in array_utils.cc

Change-Id: Ie38e257df59bf1884ef431d5d25b3c5ac0dde7a1

internal/ceres/array_utils.cc

diff --git a/internal/ceres/array_utils.cc b/internal/ceres/array_utils.cc
index e97ef6e..3247ba9 100644
--- a/internal/ceres/array_utils.cc
+++ b/internal/ceres/array_utils.cc
@@ -52,7 +52,7 @@
   return true;
 }
 
-int FindInvalidValue(const int64_t size, const double* x) {
+int64_t FindInvalidValue(const int64_t size, const double* x) {
   if (x == nullptr) {
     return size;
   }

internal/ceres/file.cc

diff --git a/internal/ceres/file.cc b/internal/ceres/file.cc
index a5338d5..361d293 100644
--- a/internal/ceres/file.cc
+++ b/internal/ceres/file.cc
@@ -58,12 +58,12 @@
 
   // Resize the input buffer appropriately.
   fseek(file_descriptor, 0L, SEEK_END);
-  int num_bytes = ftell(file_descriptor);
+  int64_t num_bytes = ftell(file_descriptor);
   data->resize(num_bytes);
 
   // Read the data.
   fseek(file_descriptor, 0L, SEEK_SET);
-  int num_read =
+  int64_t num_read =
       fread(&((*data)[0]), sizeof((*data)[0]), num_bytes, file_descriptor);
   if (num_read != num_bytes) {
     LOG(FATAL) << "Couldn't read all of " << filename