Update some URLs in BUILDING.md.
Reviewed-by: Adam Langley <firstname.lastname@example.org>
diff --git a/BUILDING.md b/BUILDING.md
index 02f8f11..47fbe0d 100644
@@ -2,14 +2,14 @@
## Build Prerequisites
- * [CMake](http://www.cmake.org/download/) 2.8.8 or later is required.
+ * [CMake](https://cmake.org/download/) 2.8.8 or later is required.
* Perl 5.6.1 or later is required. On Windows,
[Strawberry Perl](http://strawberryperl.com/) and MSYS Perl have both been
reported to work. If not found by CMake, it may be configured explicitly by
- * On Windows you currently must use [Ninja](https://martine.github.io/ninja/)
+ * On Windows you currently must use [Ninja](https://ninja-build.org/)
to build; on other platforms, it is not required, but recommended, because
it makes builds faster.