toolchain-buildroot: update glibc comment for noMMU

glibc is not available for noMMU platforms, so it doesn't make sense
to show the comment about glibc requiring dynamic libraries on noMMU
platforms.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

toolchain/toolchain-buildroot/Config.in

@@ -83,6 +83,7 @@ config BR2_TOOLCHAIN_BUILDROOT_GLIBC
 	  http://www.gnu.org/software/libc/
 
 comment "(e)glibc only available with shared lib support"
+	depends on BR2_USE_MMU
 	depends on BR2_STATIC_LIBS
 
 config BR2_TOOLCHAIN_BUILDROOT_MUSL