enable CONFIG_LTO_CLANG_FULL

extra-configs/optimize_lto.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+
+./scripts/config --file .config --enable LTO_CLANG_FULL
+# Q: What requires this option to be enabled?
+# A: Enabling this option adds support for Clang's Link Time Optimization,
+#    resulting in a nice performance uplift.
+#
+# Q: Why wasn't this option enabled by `make defconfig`?
+# A: There are two reasons for this:
+#    1. The "FULL" LTO option uses a lot of RAM during build-time.
+#    2. Just like '-O3', "FULL" LTO means a "bigger" kernel.
+#
+#    Both point are discussed here:
+#    https://github.com/ClangBuiltLinux/linux/issues/1643/