objtool/klp: Fix vmlinux .klp.symid link error for .no_trim_symbol symbols

Testing klp-build with arm64 produced the following linker error during
the original kernel build:

  `__notrim.1' referenced in section `.klp.symid' of vmlinux.o: defined in discarded section `.no_trim_symbol' of vmlinux.o

symbol_get() puts a static __notrim[] in .no_trim_symbol, which GCC
names __notrim.1, __notrim.2, etc.  Two or more built-in translation
units calling symbol_get() thus produce duplicate names, resulting in
corresponding .klp.symid references which trigger the above error.

Add .no_trim_symbol to the discarded section list so its symbols don't
get symids.

Note this issue is not specific to arm64: it just needs two built-in
symbol_get() callers.  arm64 trips over it easily because it has KVM
always compiled in vmlinux, whereas on x86 it's typically a module.

Fixes: 029223d301 ("objtool/klp: Add .klp.symid for sympos disambiguation")
Acked-by: Song Liu <song@kernel.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Link: https://patch.msgid.link/5a3cc4cded743167dd0878220201d80f7e48e5d7.1786138493.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

tools/objtool/klp-symid.c

@@ -31,6 +31,7 @@
 static const char * const discarded_secs[] = {
 	".discard",
 	".modinfo",
+	".no_trim_symbol",
 	"__tracepoint_check",
 };