Include public API declaration for cross-checking.

src/core/ppm_combinatorics_c.c

@@ -54,6 +54,7 @@
 #include "core/ppm_xfuncs.h"
 #include "core/yarandom.h"
 #include "core/ppm_visibility.h"
+#include "core/ppm_combinatorics.h"
 
 int PPM_DSO_API_EXPORT
 PPM_prime_factorization_32(uint32_t n, uint32_t **factors)

src/core/qsort_r.c

@@ -42,6 +42,7 @@
 #include <omp.h>
 #endif
 
+#include "core/qsort_r.h"
 #include "core/fptr_api.h"
 #include "core/minmax.h"
 #include "core/swapmacros.h"