watchman: patch fixes build

srcpkgs/watchman/patches/fix_autogen.patch

@@ -0,0 +1,13 @@
+From: https://github.com/facebook/watchman/issues/937#issuecomment-904717182
+
+--- a/autogen.sh
++++ b/autogen.sh
+@@ -21,7 +21,7 @@ automake --add-missing --foreign
+ # should be the case provided pkg-config is installed AND the above commands
+ # have been run to prep the source tree with local set-up.
+ CHECK_PKG_CONFIG_M4='m4_ifdef([PKG_CHECK_MODULES], [errprint([ok])])'
+-if [ "x$(autoconf <(echo "$CHECK_PKG_CONFIG_M4") 2>&1)" != "xok" ] ; then
++if [ "x$(autoconf --warnings=none <(echo "$CHECK_PKG_CONFIG_M4") 2>&1)" != "xok" ] ; then
+   echo 'pkg-config appears to be missing (not available to autoconf tools)'
+   echo 'please install the pkg-config package for your system.'
+   exit 1