linux: fix build with host-gcc 10+

Some older versions of linux, or custom versions (like forks for some
boards), fail to build with host-gcc 10+, because of redefined symbols:

      HOSTLD  scripts/dtc/dtc
    /usr/bin/ld: scripts/dtc/dtc-parser.tab.o:(.bss+0x10): multiple definition
    of `yylloc'; scripts/dtc/dtc-lexer.lex.o:(.bss+0x0): first defined here
    collect2: error: ld returned 1 exit status

Since this has been fixed in recent-ish versions, we can't use an
unconditionaly patch, so we must have a conditional patch. However, a
patch may not always apply to arbitrary Linux versions or forks.

Upstream just dropped that line altogether:
    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e33a814e772cdc36436c8c188d8c42d019fda639

So, we use a little sed-grep combo to do the exact same change.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reviewed-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Tested-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit 9b41b54be07711c10ad13ce157be272ed1cf402e)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

linux/linux.mk

@@ -260,6 +260,13 @@ endef
 
 LINUX_POST_PATCH_HOOKS += LINUX_APPLY_LOCAL_PATCHES
 
+# Older versions break on gcc 10+ because of redefined symbols
+define LINUX_DROP_YYLLOC
+	$(Q)grep -Z -l -r -E '^YYLTYPE yylloc;$$' $(@D) \
+	|xargs -0 -r $(SED) '/^YYLTYPE yylloc;$$/d'
+endef
+LINUX_POST_PATCH_HOOKS += LINUX_DROP_YYLLOC
+
 # Older linux kernels use deprecated perl constructs in timeconst.pl
 # that were removed for perl 5.22+ so it breaks on newer distributions
 # Try a dry-run patch to see if this applies, if it does go ahead