Update BUILDING documentation regarding Go.

Go is not required for running all the tests and bash isn't.

Change-Id: I04d5981dbd2203e8bae27a1265a5db5e35ae5279
Reviewed-on: https://boringssl-review.googlesource.com/3450
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/BUILDING b/BUILDING
index 18ddde1..4b2ba05 100644
--- a/BUILDING
+++ b/BUILDING
@@ -17,10 +17,8 @@
     with Platform SDK 8.1 or later are supported. Recent versions of GCC and
     Clang should work on non-Windows platforms, and maybe on Windows too.
 
-  * Bash is required for running some tests, but not for building.
-
-  * Go[5] is required for running some tests, but not for building. Note that
-    these tests do not work on Windows.
+  * Go[5] is required for running tests, but not for building. Note that the
+    runner.go tests do not work on Windows.
 
 Using Ninja (note the 'N' is capitalized in the cmake invocation):