backports: add iproute2 compile fix

Signed-off-by: John Crispin <john@phrozen.org>

backports/0030-iproute2-m_xt.so-depends-on-dynsyms.list.patch

@@ -0,0 +1,47 @@
+From 4b2e6bb352b400e244646a7bc59bc5ca3ca6f5df Mon Sep 17 00:00:00 2001
+From: Roman Yeryomin <roman@advem.lv>
+Date: Fri, 3 Sep 2021 17:31:11 +0300
+Subject: [PATCH 32/32] iproute2: m_xt.so depends on dynsyms.list
+
+When doing parallel build on a fast machine with bottleneck in i/o,
+m_xt.so may start linking faster than dynsyms.list gets populated,
+resulting in error:
+
+ld:dynsyms.list:0: syntax error in dynamic list
+
+Fix this by adding dynsyms.list as make dependency to m_xt.so
+Described also here:
+https://bugs.openwrt.org/index.php?do=details&task_id=3353
+
+Change from v1:
+- add dynsysms.list dependancy only when shared libs are enabled
+
+Signed-off-by: Roman Yeryomin <roman@advem.lv>
+Fixes: FS#3353
+---
+ .../utils/iproute2/patches/175-reduce-dynamic-syms.patch       | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/package/network/utils/iproute2/patches/175-reduce-dynamic-syms.patch b/package/network/utils/iproute2/patches/175-reduce-dynamic-syms.patch
+index da961a183b..c3892e5a0e 100644
+--- a/package/network/utils/iproute2/patches/175-reduce-dynamic-syms.patch
++++ b/package/network/utils/iproute2/patches/175-reduce-dynamic-syms.patch
+@@ -26,13 +26,14 @@
+  
+  q_atm.so: q_atm.c
+  	$(QUIET_CC)$(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) -shared -fpic -o q_atm.so q_atm.c -latm
+-@@ -205,4 +206,15 @@ static-syms.h: $(wildcard *.c)
++@@ -205,4 +206,16 @@ static-syms.h: $(wildcard *.c)
+  		sed -n '/'$$s'[^ ]* =/{s:.* \([^ ]*'$$s'[^ ]*\) .*:extern char \1[] __attribute__((weak)); if (!strcmp(sym, "\1")) return \1;:;p}' $$files ; \
+  	done > $@
+  
+ +else
+ +
+ +tc: dynsyms.list
+++m_xt.so: dynsyms.list
+ +dynsyms.list: $(wildcard *.c)
+ +	files="$(filter-out $(patsubst %.so,%.c,$(TCSO)), $^)" ; \
+ +	echo "{" > $@ ; \
+-- 
+2.25.1
+