devel/objfw: add BTCFI landing pads for amd64 and arm64

This adds missing landing pads for amd64 and arm64. Not sure if for
upstream a <cet.h> dance using _CET_ENDBR would be preferable. For the
port I kept it simple.

ld: warning: objc_msg_lookup: missing endbr64
ld: warning: objc_msg_lookup_stret: missing endbr64
ld: warning: objc_msg_lookup_super: missing endbr64
ld: warning: objc_msg_lookup_super_stret: missing endbr64
ld: warning: OFForward: missing endbr64
ld: warning: OFForward_stret: missing endbr64

Index: Makefile
===================================================================
RCS file: /cvs/ports/devel/objfw/Makefile,v
diff -u -p -r1.6 Makefile
--- Makefile 24 Jan 2024 21:08:06 -0000 1.6
+++ Makefile 24 Feb 2024 18:50:12 -0000
@@ -1,6 +1,7 @@
COMMENT = portable, lightweight framework for the Objective-C language

DISTNAME = objfw-1.0.8
+REVISION = 0

SHARED_LIBS += objfw 0.0
SHARED_LIBS += objfwrt 0.0
Index: patches/patch-src_forwarding_forwarding-amd64-elf_S
===================================================================
RCS file: patches/patch-src_forwarding_forwarding-amd64-elf_S
diff -N patches/patch-src_forwarding_forwarding-amd64-elf_S
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_forwarding_forwarding-amd64-elf_S 24 Feb 2024 18:53:27 -0000
@@ -0,0 +1,19 @@
+Index: src/forwarding/forwarding-amd64-elf.S
+--- src/forwarding/forwarding-amd64-elf.S.orig
++++ src/forwarding/forwarding-amd64-elf.S
+@@ -22,6 +22,7 @@
+
+ .section .text
+ OFForward:
++ endbr64
+ pushq %rbp
+ movq %rsp, %rbp
+
+@@ -107,6 +108,7 @@ OFForward:
+ .size OFForward, .-OFForward
+
+ OFForward_stret:
++ endbr64
+ pushq %rbp
+ movq %rsp, %rbp
+
Index: patches/patch-src_forwarding_forwarding-arm64-elf_S
===================================================================
RCS file: patches/patch-src_forwarding_forwarding-arm64-elf_S
diff -N patches/patch-src_forwarding_forwarding-arm64-elf_S
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_forwarding_forwarding-arm64-elf_S 24 Feb 2024 18:53:27 -0000
@@ -0,0 +1,11 @@
+Index: src/forwarding/forwarding-arm64-elf.S
+--- src/forwarding/forwarding-arm64-elf.S.orig
++++ src/forwarding/forwarding-arm64-elf.S
+@@ -23,6 +23,7 @@
+ .section .text
+ OFForward:
+ OFForward_stret:
++ bti c
+ stp fp, lr, [sp, #-208]!
+ mov fp, sp
+ sub sp, sp, #208
Index: patches/patch-src_runtime_lookup-asm_lookup-asm-amd64-elf_S
===================================================================
RCS file: patches/patch-src_runtime_lookup-asm_lookup-asm-amd64-elf_S
diff -N patches/patch-src_runtime_lookup-asm_lookup-asm-amd64-elf_S
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_runtime_lookup-asm_lookup-asm-amd64-elf_S 24 Feb 2024 18:53:27 -0000
@@ -0,0 +1,19 @@
+Index: src/runtime/lookup-asm/lookup-asm-amd64-elf.S
+--- src/runtime/lookup-asm/lookup-asm-amd64-elf.S.orig
++++ src/runtime/lookup-asm/lookup-asm-amd64-elf.S
+@@ -25,6 +25,7 @@
+ .section .text
+ .macro GENERATE_LOOKUP name notFound
+ \name:
++ endbr64
+ testq %rdi, %rdi
+ jz returnNilMethod
+
+@@ -68,6 +69,7 @@
+
+ .macro GENERATE_LOOKUP_SUPER name lookup
+ \name:
++ endbr64
+ movq %rdi, %r8
+ movq (%rdi), %rdi
+ testq %rdi, %rdi
Index: patches/patch-src_runtime_lookup-asm_lookup-asm-arm64-elf_S
===================================================================
RCS file: patches/patch-src_runtime_lookup-asm_lookup-asm-arm64-elf_S
diff -N patches/patch-src_runtime_lookup-asm_lookup-asm-arm64-elf_S
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-src_runtime_lookup-asm_lookup-asm-arm64-elf_S 24 Feb 2024 18:53:27 -0000
@@ -0,0 +1,19 @@
+Index: src/runtime/lookup-asm/lookup-asm-arm64-elf.S
+--- src/runtime/lookup-asm/lookup-asm-arm64-elf.S.orig
++++ src/runtime/lookup-asm/lookup-asm-arm64-elf.S
+@@ -25,6 +25,7 @@
+ .section .text
+ .macro GENERATE_LOOKUP name notFound
+ \name:
++ bti c
+ cbz x0, returnNilMethod
+
+ tst x0, #1
+@@ -68,6 +69,7 @@
+
+ .macro GENERATE_LOOKUP_SUPER name lookup
+ \name:
++ bti c
+ mov x2, x0
+ ldr x0, [x0]
+ cbz x0, returnNilMethod