CMake: Add NLOPT_VERSION in config (#262)

* CMake: Add NLOPT_VERSION in config

* Fix few more warnings

cmake/NLoptConfig.cmake.in

@@ -6,6 +6,8 @@ endif ()
 
 # Tell the user project where to find our headers and libraries
 
+set (NLOPT_VERSION "@NLOPT_VERSION_STRING@")
+
 set (NLOPT_INCLUDE_DIRS "${CMAKE_CURRENT_LIST_DIR}/@RELATIVE_NLOPT_INCLUDE_DIRS@")
 set (NLOPT_LIBRARY_DIRS "${CMAKE_CURRENT_LIST_DIR}/@RELATIVE_NLOPT_LIB_DIR@")
 

src/util/nlopt-util.h

@@ -39,7 +39,7 @@
 #ifndef HAVE_COPYSIGN
    /* not quite right for y == -0, but good enough for us */
 #  define copysign(x, y) ((y) < 0 ? -fabs(x) : fabs(x))
-#elif __STDC_VERSION__ < 199901 && !defined(__cplusplus)
+#elif !defined(__cplusplus) && __STDC_VERSION__ < 199901
 extern double copysign(double x, double y); /* may not be declared in C89 */
 #endif
 

src/util/qsort_r.c

@@ -172,16 +172,18 @@ static int qsort_cmp_wrap(const void *a, const void *b, void *thunk)
   qsort_wrapper *wrap = (qsort_wrapper *) thunk;
   return (*wrap->compar)(wrap->thunk, a, b);
 }
+
+extern void qsort_r(void *base, size_t nmemb, size_t size,
+                    int (*compar)(const void *, const void *, void *),
+                    void *arg);
 #endif
 
+
 void nlopt_qsort_r(void *base_, size_t nmemb, size_t size, void *thunk, cmp_t* compar)
 {
 #if defined(HAVE_QSORT_R) && (defined(__APPLE__) || defined(__FreeBSD__))
     qsort_r(base_, nmemb, size, thunk, compar);
 #elif defined(HAVE_QSORT_R) && defined(__linux__)
-    extern void qsort_r(void *base, size_t nmemb, size_t size,
-                        int (*compar)(const void *, const void *, void *),
-                        void *arg);
     qsort_wrapper wrapper;
     wrapper.compar = compar;
     wrapper.thunk = thunk;