Made mask unsigned to avoid shifting into sign bit.

The last iteration of the loop execute 1<<63, which would push the
result into the signed bit of a signed 64 bit type, and this
move into currently undefined behaviour with C99.  Avoid the
issue by making the operation work on unsigned 64 bit type instead.

This require libogg version to 1.3.4, raise autotools dependency check
to look for this.

Partly solves github issue #18.

configure.ac

@@ -392,7 +392,7 @@ dnl check for pkg-config itself so we don't try the m4 macro without pkg-config
 AC_CHECK_PROG(HAVE_PKG_CONFIG, pkg-config, yes)
 if test "x$HAVE_PKG_CONFIG" = "xyes"
 then
-  PKG_CHECK_MODULES(OGG, ogg >= 1.1, HAVE_OGG=yes, HAVE_OGG=no)
+  PKG_CHECK_MODULES(OGG, ogg >= 1.3.4, HAVE_OGG=yes, HAVE_OGG=no)
 fi
 if test "x$HAVE_OGG" = "xno"
 then
@@ -407,7 +407,7 @@ then
   CFLAGS="$CFLAGS $OGG_CFLAGS"
   LIBS="$LIBS $OGG_LIBS"
   AC_CHECK_FUNC(oggpackB_read, , [
-    AC_MSG_ERROR([newer libogg version (1.1 or later) required])
+    AC_MSG_ERROR([newer libogg version (1.3.4 or later) required])
   ])
   CFLAGS=$cflags_save
   LIBS=$libs_save

lib/state.c

@@ -388,7 +388,7 @@ static void oc_state_border_init(oc_theora_state *_state){
         /*Otherwise, check to see if it straddles the border.*/
         else if(x<crop_x0&&crop_x0<x+8||x<crop_xf&&crop_xf<x+8||
          y<crop_y0&&crop_y0<y+8||y<crop_yf&&crop_yf<y+8){
-          ogg_int64_t mask;
+          ogg_uint64_t mask;
           int         npixels;
           int         i;
           mask=npixels=0;
@@ -396,7 +396,7 @@ static void oc_state_border_init(oc_theora_state *_state){
             int j;
             for(j=0;j<8;j++){
               if(x+j>=crop_x0&&x+j<crop_xf&&y+i>=crop_y0&&y+i<crop_yf){
-                mask|=(ogg_int64_t)1<<(i<<3|j);
+                mask|=(ogg_uint64_t)1<<(i<<3|j);
                 npixels++;
               }
             }