Subject: Only use -fstack-protector-all if it is supported

This flag isn't available on all Debian ports.

Origin: vendor
From: Colin Watson <cjwatson@debian.org>
Reviewed-by: nicoo <nicoo@debian.org>
Forwarded: https://github.com/Yubico/libfido2/pull/130
Applied-Upstream: not-yet
Last-Update: 2020-02-23

---
 CMakeLists.txt | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c7c5991..07ca5e1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -114,7 +114,10 @@ else()
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wbad-function-cast")
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pedantic")
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -pedantic-errors")
-	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstack-protector-all")
+	check_c_compiler_flag("-fstack-protector-all" HAVE_STACK_PROTECTOR_ALL)
+	if(HAVE_STACK_PROTECTOR_ALL)
+		set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fstack-protector-all")
+	endif()
 	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
 
 	set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g2")