kconfig: move CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED to Kconfig

If this option is enabled, the objects under lib/ directory
are compiled with speed optimization, not size optimization.
(Currently, only used by some Blackfin boards.)

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/Kconfig b/lib/Kconfig
index 9724eb8..88e5da7 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -1,3 +1,11 @@
 menu "Library routines"
 
+config CC_OPTIMIZE_LIBS_FOR_SPEED
+	bool "Optimize libraries for speed"
+	help
+	  Enabling this option will pass "-O2" to gcc when compiling
+	  under "lib" directory.
+
+	  If unsure, say N.
+
 endmenu