[OE-core] [PATCH] security_flags: Add comment about what it does and who uses it

[Richard Purdie]

It was pointed out that people couldn't easily see who used this or
why so add some comments about that.

Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>

diff --git a/meta/conf/distro/include/security_flags.inc b/meta/conf/distro/include/security_flags.inc
index 0ee3814..9608c7f 100644
--- a/meta/conf/distro/include/security_flags.inc
+++ b/meta/conf/distro/include/security_flags.inc
@@ -1,3 +1,10 @@
+# Setup extra CFLAGS and LDFLAGS which have 'security' benefits. These 
+# don't work universally, there are recipes which can't use one, the other
+# or both so a blacklist is maintained here. The idea would be over
+# time to reduce this list to nothing.
+# From a Yocto Project perspective, this file is included and tested
+# in the DISTRO="poky-lsb" configuration.
+
 SECURITY_CFLAGS ?= "-fstack-protector-all -pie -fpie -D_FORTIFY_SOURCE=2"
 SECURITY_NO_PIE_CFLAGS ?= "-fstack-protector-all -D_FORTIFY_SOURCE=2"
 SECURITY_LDFLAGS ?= "-Wl,-z,relro,-z,now"