rt: make jemalloc header conform to android signature.

Author: graydon

src/rt/jemalloc/configure.ac

@@ -257,6 +257,15 @@ case "${host}" in
 	AC_DEFINE([JEMALLOC_PURGE_MADVISE_FREE], [ ])
 	force_lazy_lock="1"
 	;;
+  *-*-linux-android*)
+	CFLAGS="$CFLAGS"
+	CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"
+	abi="elf"
+	AC_DEFINE([JEMALLOC_HAS_ALLOCA_H])
+	AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED], [ ])
+	AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
+	default_munmap="0"
+	;;
   *-*-linux*)
 	CFLAGS="$CFLAGS"
 	CPPFLAGS="$CPPFLAGS -D_GNU_SOURCE"