configure: work around modff() not existing

Happens on HP-UX/PA-RISC.

Thanks to Richard Lloyd for reporting the issue.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

config/hwloc.m4

@@ -444,8 +444,15 @@ EOF])
 
     AC_CHECK_DECLS([fabsf], [
       AC_CHECK_LIB([m], [fabsf],
-                   [HWLOC_LIBS="-lm $HWLOC_LIBS"])
+                   [need_libm=yes])
     ], [], [[#include <math.h>]])
+    AC_CHECK_DECLS([modff], [
+      AC_CHECK_LIB([m], [modff],
+                   [need_libm=yes])
+    ], [], [[#include <math.h>]])
+    if test x$need_libm = xyes; then
+      HWLOC_LIBS="-lm $HWLOC_LIBS"
+    fi
 
     AC_CHECK_HEADERS([picl.h], [
       AC_CHECK_LIB([picl], [picl_initialize],

contrib/windows/private_config.h

@@ -59,6 +59,10 @@
    */
 #define HAVE_DECL_FABSF 1
 
+/* Define to 1 if you have the declaration of `modff', and to 0 if you don't.
+   */
+#define HAVE_DECL_MODFF 1
+
 /* Define to 1 if you have the declaration of `HW_NCPU', and to 0 if you
    don't. */
 /* #undef HAVE_DECL_HW_NCPU */

include/private/misc.h

@@ -517,6 +517,10 @@ hwloc__obj_type_is_icache(hwloc_obj_type_t type)
 #define fabsf(f) fabs((double)(f))
 #endif
 
+#if !HAVE_DECL_MODFF
+#define modff(x,iptr) (float)modf((double)x,(double *)iptr)
+#endif
+
 #if HAVE_DECL__SC_PAGE_SIZE
 #define hwloc_getpagesize() sysconf(_SC_PAGE_SIZE)
 #elif HAVE_DECL__SC_PAGESIZE