menuconfig: add help description for Stack Smashing Protection options

Descriptions taken from:
https://wiki.osdev.org/Stack_Smashing_Protector

Signed-off-by: Marius Dinu <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/16897
Signed-off-by: Christian Marangi <[email protected]>
(cherry picked from commit cbf7be9fb37baaaf7ee5c2b6315028bd47c764bc)
Link: https://github.com/openwrt/openwrt/pull/17097
Signed-off-by: Petr Štetiar <[email protected]>

config/Config-build.in

@@ -295,12 +295,22 @@ menu "Global build settings"
 		  Enable GCC Stack Smashing Protection (SSP) for userspace applications
 		config PKG_CC_STACKPROTECTOR_NONE
 			bool "None"
+			help
+				No stack smashing protection.
 		config PKG_CC_STACKPROTECTOR_REGULAR
 			bool "Regular"
+			help
+				Protects functions with vulnerable objects.
+				This includes functions with buffers larger than 8 bytes or calls to alloca.
 		config PKG_CC_STACKPROTECTOR_STRONG
 			bool "Strong"
+			help
+				Like Regular, but also protects functions with
+				local arrays or references to local frame addresses.
 		config PKG_CC_STACKPROTECTOR_ALL
 			bool "All"
+			help
+				Protects all functions.
 	endchoice
 
 	choice
@@ -310,10 +320,18 @@ menu "Global build settings"
 		  Enable GCC Stack-Smashing Protection (SSP) for the kernel
 		config KERNEL_CC_STACKPROTECTOR_NONE
 			bool "None"
+			help
+				No stack smashing protection.
 		config KERNEL_CC_STACKPROTECTOR_REGULAR
 			bool "Regular"
+			help
+				Protects functions with vulnerable objects.
+				This includes functions with buffers larger than 8 bytes or calls to alloca.
 		config KERNEL_CC_STACKPROTECTOR_STRONG
 			bool "Strong"
+			help
+				Like Regular, but also protects functions with
+				local arrays or references to local frame addresses.
 	endchoice
 
 	config KERNEL_STACKPROTECTOR