test for __compar_fn_t and if not defined by libc then define it
help make directfb compile with musl

Upstream-Status: Pending
Signed-off-by: Khem Raj <raj.khem@gmail.com>

Index: DirectFB-1.7.7/configure.in
===================================================================
--- DirectFB-1.7.7.orig/configure.in
+++ DirectFB-1.7.7/configure.in
@@ -112,6 +112,17 @@ AC_CHECK_SIZEOF(long)
 AC_CHECK_SIZEOF(long long)
 AC_CHECK_FUNCS(fork)
 
+AC_CACHE_CHECK([for compar_fn_t in stdlib.h],ccache_cv_COMPAR_FN_T, [
+    AC_TRY_COMPILE(
+        [#include <stdlib.h>],
+        [void test_fn(void) { qsort(NULL, 0, 0, (__compar_fn_t)NULL); }],
+        ccache_cv_COMPAR_FN_T=yes,
+        ccache_cv_COMPAR_FN_T=no)])
+if test x"$ccache_cv_COMPAR_FN_T" = x"yes"; then
+   AC_DEFINE(HAVE_COMPAR_FN_T, 1,
+             Define to 1 if you have the `__compar_fn_t' typedef.)
+fi
+
 AC_PATH_PROGS(PERL, perl5 perl)
 
 AC_PATH_PROG(MAN2HTML, man2html, no)
Index: DirectFB-1.7.7/inputdrivers/lirc/lirc.c
===================================================================
--- DirectFB-1.7.7.orig/inputdrivers/lirc/lirc.c
+++ DirectFB-1.7.7/inputdrivers/lirc/lirc.c
@@ -59,6 +59,11 @@
 
 #include <core/input_driver.h>
 
+#if HAVE_COMPAR_FN_T
+#define COMPAR_FN_T __compar_fn_t
+#else
+typedef int (*COMPAR_FN_T)(const void *, const void *);
+#endif
 
 DFB_INPUT_DRIVER( lirc )
 
@@ -97,7 +102,7 @@ static DFBInputDeviceKeySymbol lirc_pars
           qsort ( keynames,
                   D_ARRAY_SIZE( keynames ),
                   sizeof(keynames[0]),
-                  (__compar_fn_t) keynames_sort_compare );
+                  (COMPAR_FN_T) keynames_sort_compare );
           keynames_sorted = true;
      }
 
@@ -124,7 +129,7 @@ static DFBInputDeviceKeySymbol lirc_pars
                symbol_name = bsearch( name, keynames,
                                       D_ARRAY_SIZE( keynames ),
                                       sizeof(keynames[0]),
-                                      (__compar_fn_t) keynames_compare );
+                                      (COMPAR_FN_T) keynames_compare );
                if (symbol_name)
                     return symbol_name->symbol;
                break;