Removed extra includes from the c files

---
type: pre_push_report
description: Results of running various checks prior to pushing changes.
report:
  - task: run_javascript_examples
    status: na
  - task: run_c_examples
    status: na
  - task: run_cpp_examples
    status: na
  - task: run_javascript_readme_examples
    status: na
  - task: run_c_benchmarks
    status: na
  - task: run_cpp_benchmarks
    status: na
  - task: run_fortran_benchmarks
    status: na
  - task: run_javascript_benchmarks
    status: na
  - task: run_julia_benchmarks
    status: na
  - task: run_python_benchmarks
    status: na
  - task: run_r_benchmarks
    status: na
  - task: run_javascript_tests
    status: na
---

Author: anandkaranubc

lib/node_modules/@stdlib/stats/base/dists/arcsine/stdev/benchmark/c/benchmark.c

@@ -19,7 +19,6 @@
 #include "stdlib/stats/base/dists/arcsine/stdev.h"
 #include <stdlib.h>
 #include <stdio.h>
-#include <math.h>
 #include <time.h>
 #include <sys/time.h>
 

lib/node_modules/@stdlib/stats/base/dists/arcsine/stdev/examples/c/example.c

@@ -19,7 +19,6 @@
 #include "stdlib/stats/base/dists/arcsine/stdev.h"
 #include <stdlib.h>
 #include <stdio.h>
-#include <math.h>
 
 static double random_uniform( const double min, const double max ) {
     double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
@@ -41,11 +40,7 @@ int main( void ) {
         b = random_uniform( a, a + 40.0 );
         s = stdlib_base_dists_arcsine_stdev( a, b );
 
-        if ( isnan( s ) ) {
-            printf( "a: %lf, b: %lf, Standard Deviation: NaN (Invalid Input)\n", a, b );
-        } else {
-            printf( "a: %lf, b: %lf, Standard Deviation: %lf\n", a, b, s );
-        }
+        printf( "a: %lf, b: %lf, Standard Deviation: %lf\n", a, b, s );
     }
 
     return 0;

lib/node_modules/@stdlib/stats/base/dists/arcsine/stdev/src/main.c

@@ -16,8 +16,6 @@
 * limitations under the License.
 */
 
-#include <math.h>
-#include <stdbool.h>
 #include "stdlib/math/base/assert/is_nan.h"
 
 // CONSTANTS
@@ -60,7 +58,7 @@ double stdlib_base_dists_arcsine_stdev( const double a, const double b ) {
         stdlib_base_is_nan( b ) ||
         a >= b
     ) {
-        return NAN;
+        return 0.0 / 0.0; // NaN
     }
     return SQRT1OVER8 * ( b - a );
 }