[lld][ELF][Morello] Align fragment bases of exec symbols pointed by [I]RELATIVE relocs

The executable capabilities created by [I]RELATIVE relocations used the
symbol value for the base, and the symbol size as the capability limit.
This results in the executable capabilities being too narrow that they
could not call other functions.

Fix this by encoding fragments for these relocations in a way similar to
how the cap relocs for executable capabilities are encoded in the static
linking case; i.e. set the bounds to cover the .text + .ro + .rel.ro regions.
11 jobs for !135 with morello_cap_bounds_for_exec_symbol_dynrelocs in 218 minutes and 6 seconds (queued for 36 seconds)
latest detached
Status Job ID Name Coverage
  Build Stage1
passed #63774
build-and-test-cheribsd

01:38:07

passed #63773
arm64_fast
build-musl

00:36:08

passed #63772
build-toolchain

01:51:58

 
  Build Stage2
passed #63775
build-android

01:09:19

passed #63776
build-busybox

00:07:45

passed #63777
build-firmware

00:07:19

 
  Generate Test
passed #63778
generate-test

00:01:44

 
  Test
passed test

passed #63780
arm64
test-busybox

00:02:53

passed #63782
arm64_fast
test-musl

00:02:00

passed #63781
arm64
test-tuxsuite-busybox

00:00:20