STATIC_PAGE_SHIFT for cross-compiling jemalloc

Sets `STATIC_PAGE_SHIFT` for cross-compiling jemalloc to 12. A
shift of 12 represents a page size of 4k for practically all
platforms.
diff --git a/configure.ac b/configure.ac
index 04bb294..58f6289 100644
--- a/configure.ac
+++ b/configure.ac
@@ -968,7 +968,8 @@
     return 0;
 ]])],
                              [je_cv_static_page_shift=`cat conftest.out`],
-                             [je_cv_static_page_shift=undefined]))
+                             [je_cv_static_page_shift=undefined],
+                             [je_cv_static_page_shift=12]))
 
 if test "x$je_cv_static_page_shift" != "xundefined"; then
    AC_DEFINE_UNQUOTED([STATIC_PAGE_SHIFT], [$je_cv_static_page_shift])