Compilation error fixes

- In C you're not allowed to define variables in the middle
  of the block. This was violated in curve_fitting.c by
  calling ceres_init() in the beginning of main() and declaring
  variables later.

- Also ifdef-ed suitesparse stuff in covariance estimation module.
  This solves compilation error when you don't have suitesparse
  compiled/installed.

Change-Id: I22b543c09ea01f55e127079daade99a0b781f789

examples/curve_fitting.c

diff --git a/examples/curve_fitting.c b/examples/curve_fitting.c
index a2fb5b9..5e3cd16 100644
--- a/examples/curve_fitting.c
+++ b/examples/curve_fitting.c
@@ -144,18 +144,21 @@
 }
 
 int main(int argc, char** argv) {
-  ceres_init(argc, argv);
-
   /* Note: Typically it is better to compact m and c into one block,
    * but in this case use separate blocks to illustrate the use of
    * multiple parameter blocks. */
   double m = 0.0;
   double c = 0.0;
+
   double *parameter_pointers[] = { &m, &c };
   int parameter_sizes[] = { 1, 1 };
 
-  ceres_problem_t* problem = ceres_create_problem();
+  ceres_problem_t* problem;
   int i;
+
+  ceres_init(argc, argv);
+
+  problem = ceres_create_problem();
   for (i = 0; i < num_observations; ++i) {
     ceres_problem_add_residual_block(
         problem,

internal/ceres/covariance_impl.h

diff --git a/internal/ceres/covariance_impl.h b/internal/ceres/covariance_impl.h
index 42b262e..0be53e7 100644
--- a/internal/ceres/covariance_impl.h
+++ b/internal/ceres/covariance_impl.h
@@ -80,7 +80,9 @@
   map<const double*, int> parameter_block_to_row_index_;
   set<const double*> constant_parameter_blocks_;
   scoped_ptr<CompressedRowSparseMatrix> covariance_matrix_;
+#ifndef CERES_NO_SUITESPARSE
   SuiteSparse ss_;
+#endif
 };
 
 }  // namespace internal