kbuild: trivial - fix the help doc of CONFIG_CC_OPTIMIZE_FOR_SIZE

Other than GCC, we have another choice, Clang for building the kernel
these days.  It seems better to say "compiler" rather than "gcc".
Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

init/Kconfig

@@ -1299,8 +1299,8 @@ config INIT_FALLBACK
 config CC_OPTIMIZE_FOR_SIZE
 	bool "Optimize for size"
 	help
-	  Enabling this option will pass "-Os" instead of "-O2" to gcc
-	  resulting in a smaller kernel.
+	  Enabling this option will pass "-Os" instead of "-O2" to
+	  your compiler resulting in a smaller kernel.
 
 	  If unsure, say N.