scripts/faddr2line: Check only two symbols when calculating symbol size

Rather than looping through each symbol in a particular section to
calculate a symbol's size, grep for the symbol and its immediate
successor, and only use those two symbols.
Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Link: https://lore.kernel.org/r/20240415145538.1938745-8-bjohannesmeyer@gmail.comSigned-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

scripts/faddr2line

@@ -252,7 +252,7 @@ __faddr2line() {
 				found=2
 				break
 			fi
-		done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
+		done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2 | ${GREP} -A1 --no-group-separator " ${sym_name}$")
 
 		if [[ $found = 0 ]]; then
 			warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"