elf: Also compile dl-misc.os with $(rtld-early-cflags)

Also compile dl-misc.os with $(rtld-early-cflags) to avoid

Program received signal SIGILL, Illegal instruction.
0x00007ffff7fd36ea in _dl_strtoul (nptr=nptr@entry=0x7fffffffe2c9 "2",
    endptr=endptr@entry=0x7fffffffd728) at dl-misc.c:156
156	  bool positive = true;
(gdb) bt
 #0  0x00007ffff7fd36ea in _dl_strtoul (nptr=nptr@entry=0x7fffffffe2c9 "2",
    endptr=endptr@entry=0x7fffffffd728) at dl-misc.c:156
 #1  0x00007ffff7fdb1a9 in tunable_initialize (
    cur=cur@entry=0x7ffff7ffbc00 <tunable_list+2176>,
    strval=strval@entry=0x7fffffffe2c9 "2", len=len@entry=1)
    at dl-tunables.c:131
 #2  0x00007ffff7fdb3a2 in parse_tunables (valstring=<optimized out>)
    at dl-tunables.c:258
 #3  0x00007ffff7fdb5d9 in __GI___tunables_init (envp=0x7fffffffdd58)
    at dl-tunables.c:288
 #4  0x00007ffff7fe44c3 in _dl_sysdep_start (
    start_argptr=start_argptr@entry=0x7fffffffdcb0,
    dl_main=dl_main@entry=0x7ffff7fe5f80 <dl_main>)
    at ../sysdeps/unix/sysv/linux/dl-sysdep.c:110
 #5  0x00007ffff7fe5cae in _dl_start_final (arg=0x7fffffffdcb0) at rtld.c:494
 #6  _dl_start (arg=0x7fffffffdcb0) at rtld.c:581
 #7  0x00007ffff7fe4b38 in _start ()
(gdb)

when setting GLIBC_TUNABLES in glibc compiled with APX.
Reviewed-by: Florian Weimer <[email protected]>

elf/Makefile

@@ -170,6 +170,7 @@ CFLAGS-.op += $(call elide-stack-protector,.op,$(elide-routines.os))
 CFLAGS-.os += $(call elide-stack-protector,.os,$(all-rtld-routines))
 
 # Add the requested compiler flags to the early startup code.
+CFLAGS-dl-misc.os += $(rtld-early-cflags)
 CFLAGS-dl-printf.os += $(rtld-early-cflags)
 CFLAGS-dl-setup_hash.os += $(rtld-early-cflags)
 CFLAGS-dl-sysdep.os += $(rtld-early-cflags)