Fix incompatible pointer type due to misuse of the gcry_md_open
function.

Submitted upstream: <https://github.com/dajobe/rasqal/pull/13>

diff --git a/configure b/configure
index 038ea7c3efaf06a0..17a107cda735a257 100755
--- a/configure
+++ b/configure
@@ -14541,7 +14541,7 @@ elif test "$ac_cv_header_gcrypt_h" = "yes"; then
 int
 main ()
 {
- gcry_md_hd_t hash; gcry_md_open(hash, GCRY_MD_MD5, 0);
+ gcry_md_hd_t hash; gcry_md_open(&hash, GCRY_MD_MD5, 0);
   ;
   return 0;
 }
diff --git a/configure.ac b/configure.ac
index 7bfc38e9261d6c96..eea4d34e7dc9fd4b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -631,7 +631,7 @@ elif test "$ac_cv_header_gcrypt_h" = "yes"; then
   LIBS="$LIBS `$LIBGCRYPT_CONFIG --libs`"
 
   AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-  #include <gcrypt.h>]], [[ gcry_md_hd_t hash; gcry_md_open(hash, GCRY_MD_MD5, 0); ]])],[have_digest_gcrypt=yes],[have_digest_gcrypt=no])
+  #include <gcrypt.h>]], [[ gcry_md_hd_t hash; gcry_md_open(&hash, GCRY_MD_MD5, 0); ]])],[have_digest_gcrypt=yes],[have_digest_gcrypt=no])
 
   CPPFLAGS="$oCPPFLAGS"
   LIBS="$oLIBS"