SDL: cmake: Remove libunwind-generic as hard dependency

SDL Commits
1 
From fcf0e524bb718471b07844a1323ea6253feba180 Mon Sep 17 00:00:00 2001
From: Khem Raj <[EMAIL REDACTED]>
Date: Fri, 7 Jan 2022 11:17:47 -0800
Subject: [PATCH] cmake: Remove libunwind-generic as hard dependency

when using alternate unwind implementations like LLVM libunwind
this library is not provided yet the libunwind features are fully
implemented in main libunwind, making this hard dependency assumes
a particular libunwind implementation, this patch makes it optional
which makes the builds to work with llvm libunwind

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a0605e41ba1..50c1eae094e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1365,7 +1365,7 @@ elseif(UNIX AND NOT APPLE AND NOT ANDROID AND NOT RISCOS AND NOT HAIKU)
       if(HAVE_LIBUNWIND_H)
         # We've already found the header, so REQUIRE the lib to be present
         pkg_search_module(UNWIND REQUIRED libunwind)
-        pkg_search_module(UNWIND_GENERIC REQUIRED libunwind-generic)
+        pkg_search_module(UNWIND_GENERIC libunwind-generic)
         list(APPEND EXTRA_LIBS ${UNWIND_LIBRARIES} ${UNWIND_GENERIC_LIBRARIES})
       endif()
     endif()