x86, relocs: More relocations which may end up as absolute

GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from
section-relative to absolute if they are in a section of zero length.
This turns the symbols __init_begin and __init_end into absolute
symbols.  Let the relocs program know that those should be treated as
relative symbols.

This bug is exposed by checkin

433de739bb x86, realmode: 16-bit real-mode code support for relocs tool

only in the sense that that checkin changes the relocs tool to report
an error instead of silently generating a kernel which is broken if
relocated.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>

arch/x86/tools/relocs.c

@@ -56,7 +56,11 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  * as absolute (typically defined outside any section in the linker script.)
  */
 	[S_REL] =
-	"^(__init_begin|__init_end|_end)$"
+	"^(__init_(begin|end)|"
+	"__x86_cpu_dev_(start|end)|"
+	"(__parainstructions|__alt_instructions)(|_end)|"
+	"(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
+	"_end)$"
 };