utils/genrandconfig: fix matching for a few lines

The matching in genrandconfig is idiomatically done by matching whole
lines, i.e. with the terminating \n but a few places are missing that.

Those are only matching against '=y', a boolean symbol, so it is in
practice not causing any issue. Still, for consistency, fix those.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 8b8f5e336609e3b8f24786f8029d02bcae593a84)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/genrandconfig

@@ -279,12 +279,12 @@ async def fixup_config(sysinfo, configfile):
        'BR2_PACKAGE_FLANN=y\n' in configlines:
         return False
     # No C library for internal toolchain
-    if 'BR2_TOOLCHAIN_BUILDROOT_NONE=y' in configlines:
+    if 'BR2_TOOLCHAIN_BUILDROOT_NONE=y\n' in configlines:
         return False
     # Xtensa custom cores require an overlay file with internal
     # toolchains
-    if 'BR2_XTENSA_CUSTOM=y' in configlines and \
-       'BR2_TOOLCHAIN_BUILDROOT=y' in configlines:
+    if 'BR2_XTENSA_CUSTOM=y\n' in configlines and \
+       'BR2_TOOLCHAIN_BUILDROOT=y\n' in configlines:
         return False
 
     if 'BR2_TOOLCHAIN_BARE_METAL_BUILDROOT=y\n' in configlines: