mandoc: fix compilation with GCC10

This is probably fixed in CVS. Unfortunately, I have no idea how to
import such a patch.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

diff --git a/utils/mandoc/patches/020-gcc10.patch b/utils/mandoc/patches/020-gcc10.patch
new file mode 100644 (file)
index 0000000..fc72324
--- /dev/null
+++ b/utils/mandoc/patches/020-gcc10.patch
@@ -0,0 +1,11 @@
+--- a/compat_getline.c
++++ b/compat_getline.c
+@@ -2,7 +2,7 @@
+ 
+ #if HAVE_GETLINE
+ 
+-int dummy;
++extern int dummy;
+ 
+ #else
+