sqlite: always use memory for tempfiles.

credits to @bavison for the MAP_POPULATE patch

packages/databases/sqlite/package.mk

@@ -61,7 +61,7 @@ PKG_AUTORECONF="yes"
 # SQLITE_MAX_MMAP_SIZE can be modified at start-time using the
 # sqlite3_config(SQLITE_CONFIG_MMAP_SIZE) call, or at run-time using the
 # mmap_size pragma.
-  CFLAGS="$CFLAGS -DSQLITE_DEFAULT_MMAP_SIZE=268435456"
+  CFLAGS="$CFLAGS -DSQLITE_TEMP_STORE=3 -DSQLITE_DEFAULT_MMAP_SIZE=268435456"
 
 
 PKG_CONFIGURE_OPTS_TARGET="--enable-static \

packages/databases/sqlite/patches/sqlite-01_map_populate.patch

@@ -0,0 +1,22 @@
+diff --git a/sqlite3.c b/sqlite3.c
+index d0057a6..63b80c7 100644
+--- a/sqlite3.c
++++ b/sqlite3.c
+@@ -28278,7 +28278,7 @@ static void unixRemapfile(
+     pNew = osMremap(pOrig, nReuse, nNew, MREMAP_MAYMOVE);
+     zErr = "mremap";
+ #else
+-    pNew = osMmap(pReq, nNew-nReuse, flags, MAP_SHARED, h, nReuse);
++    pNew = osMmap(pReq, nNew-nReuse, flags, MAP_SHARED | MAP_POPULATE, h, nReuse);
+     if( pNew!=MAP_FAILED ){
+       if( pNew!=pReq ){
+         osMunmap(pNew, nNew - nReuse);
+@@ -28297,7 +28297,7 @@ static void unixRemapfile(
+
+   /* If pNew is still NULL, try to create an entirely new mapping. */
+   if( pNew==0 ){
+-    pNew = osMmap(0, nNew, flags, MAP_SHARED, h, 0);
++    pNew = osMmap(0, nNew, flags, MAP_SHARED | MAP_POPULATE, h, 0);
+   }
+
+   if( pNew==MAP_FAILED ){