package/libcec: fix build with gcc 10

Fix the following build failure with gcc 10:

/nvmedata/autobuild/instance-2/output-1/build/libcec-6.0.2/src/cec-client/../../include/cecloader.h: In function 'bool LibCecBootloader(const char*)':
/nvmedata/autobuild/instance-2/output-1/build/libcec-6.0.2/src/cec-client/../../include/cecloader.h:175:14: error: converting to 'bool' from 'std::nullptr_t' requires direct-initialization [-fpermissive]
  175 |       return NULL;
      |              ^~~~
/nvmedata/autobuild/instance-2/output-1/build/libcec-6.0.2/src/cec-client/../../include/cecloader.h:184:12: error: converting to 'bool' from 'std::nullptr_t' requires direct-initialization [-fpermissive]
  184 |     return NULL;
      |            ^~~~

Fixes:
 - http://autobuild.buildroot.org/results/e34bd78cc81e6da12a85c1e4ee76931818d91073

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 858a7fe4e59ae43b6c83d203ca6591c444618eff)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libcec/0001-cecloader-h-fix-null-return.patch

@@ -0,0 +1,37 @@
+From 452b2049b2ee3e73968c603e5524b2d349ac0c3e Mon Sep 17 00:00:00 2001
+From: psykose <alice@ayaya.dev>
+Date: Sat, 9 Apr 2022 17:59:11 +0000
+Subject: [PATCH] cecloader.h: fix null return
+
+returning NULL is invalid for a return type of bool when NULL is defined
+as `nullptr` instead of 0L
+
+[Retrieved from:
+https://github.com/Pulse-Eight/libcec/pull/599/commits/452b2049b2ee3e73968c603e5524b2d349ac0c3e]
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+---
+ include/cecloader.h | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/include/cecloader.h b/include/cecloader.h
+index be76468f..550f598e 100644
+--- a/include/cecloader.h
++++ b/include/cecloader.h
+@@ -172,7 +172,7 @@ bool LibCecBootloader(const char *strLib = NULL)
+     if (!g_libCEC)
+     {
+       std::cout << dlerror() << std::endl;
+-      return NULL;
++      return false;
+     }
+   }
+ 
+@@ -181,7 +181,7 @@ bool LibCecBootloader(const char *strLib = NULL)
+   if (!LibCecBootloader)
+   {
+     std::cout << "cannot find CECStartBootloader" << std::endl;
+-    return NULL;
++    return false;
+   }
+ 
+   bool bReturn = LibCecBootloader();