World breakage: -O2 and new libthr/libc_r code

Marcel Moolenaar's latest libthr libc_r commit seems to have broken world
for CFLAGS containing -O2.


===> lib/libthread_db
cc -O2 -pipe -fno-builtin -march=athlon-xp -I. -I/usr/src/lib/libthread_db
-Wsystem-headers -Werror -Wall -Wno-format-y2k -Wno-uninitialized -c /u
cc -fpic -DPIC -O2 -pipe -fno-builtin -march=athlon-xp -I.
-I/usr/src/lib/libthread_db -Wsystem-headers -Werror -Wall -Wno-format-y2k
-Wno-uniniti
cc -O2 -pipe -fno-builtin -march=athlon-xp -I. -I/usr/src/lib/libthread_db
-Wsystem-headers -Werror -Wall -Wno-format-y2k -Wno-uninitialized -c /u
cc -fpic -DPIC -O2 -pipe -fno-builtin -march=athlon-xp -I.
-I/usr/src/lib/libthread_db -Wsystem-headers -Werror -Wall -Wno-format-y2k
-Wno-uniniti
In file included from libpthread.h:3,
                 from /usr/src/lib/libthread_db/libpthread_db.c:41:
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_get':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:162: warning:
dereferencing type-punned pointer will break strict-aliasing rules
In file included from libpthread.h:3,
                 from /usr/src/lib/libthread_db/libpthread_db.c:41:
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_get':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:162: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_critical_leave':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:177: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_in_critical':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:183: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_tcb_get':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:195: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_critical_leave':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:177: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_kcb_in_critical':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:183: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_tcb_get':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:195: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_get_curthread':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:203: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_get_curthread':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:203: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_get_curkse':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:213: warning:
dereferencing type-punned pointer will break strict-aliasing rules
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h: In function
`_get_curkse':
/usr/src/lib/libpthread/arch/i386/include/pthread_md.h:213: warning:
dereferencing type-punned pointer will break strict-aliasing rules
*** Error code 1

/Daniel Eriksson