kconfig: move CONFIG_USE_PRIVATE_LIBGCC to Kconfig

The private libgcc is supported only on ARM, MIPS, PowerPC, SH, x86.
Those architectures should "select" HAVE_PRIVATE_LIBGCC and
CONFIG_USE_PRIVATE_LIBGCC should depend on it.

Currently, this option is enabled on Tegra boards and x86 architecture.
Move the definition from header files to Kconfig.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Tested-by: Simon Glass <sjg@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Tom Warren <twarren@nvidia.com>
diff --git a/lib/Kconfig b/lib/Kconfig
index a889c22..8460439 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -8,6 +8,17 @@
 
 	  If unsure, say N.
 
+config HAVE_PRIVATE_LIBGCC
+	bool
+
+config USE_PRIVATE_LIBGCC
+	bool "Use private libgcc"
+	depends on HAVE_PRIVATE_LIBGCC
+	help
+	  This option allows you to use the built-in libgcc implementation
+	  of U-boot instead of the one privided by the compiler.
+	  If unsure, say N.
+
 config SYS_HZ
 	int
 	default 1000