[DO-971] ffmpeg recipe with requirements (!9)

Co-authored-by: aleksandr.vodyanov <aleksandr.vodyanov@avroid.tech>
Reviewed-on: https://git.avroid.tech/Conan/conan_build/pulls/9

recipes/libalsa/all/patches/1.2.5.1-0001-control-empty-fix-the-static-build.patch

@@ -0,0 +1,25 @@
+From 81e7923fbfad45b2f353a4d6e3053af51f5f7d0b Mon Sep 17 00:00:00 2001
+From: Jaroslav Kysela <perex@perex.cz>
+Date: Tue, 15 Jun 2021 23:21:42 +0200
+Subject: [PATCH] control: empty - fix the static build
+
+Reported-by: Jan Palus <atler@pld-linux.org>
+Fixes: https://github.com/alsa-project/alsa-lib/issues/157
+Signed-off-by: Jaroslav Kysela <perex@perex.cz>
+---
+ src/control/control_empty.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/control/control_empty.c b/src/control/control_empty.c
+index 49d1026c..c9b048c1 100644
+--- a/src/control/control_empty.c
++++ b/src/control/control_empty.c
+@@ -30,7 +30,7 @@
+ 
+ #ifndef PIC
+ /* entry for static linking */
+-const char *_snd_module_ctl_empty = "";
++const char *_snd_module_control_empty = "";
+ #endif
+ 
+ /*! \page control_plugins