Header include cleanup part one.

No functional change in theory. Cleanup headers to reduce the mostly-useless
for some time now.

1) Remove common/{getopt.[ch],getopt1.c} files and remove from build. Use
   C99-required functions from <unistd.h> and <getopt.h>.

2) <inttypes.h> is required by C99 and has been required for some time. Remove
   #ifdef blocks and replace some older <stdint.h> includes.

3) <pthread.h> isn't optional at this point. PTHREAD_MUTEX_INITIALIZER is
   required throughout.

4) Use <limits.h> instead of <values.h> or <float.h>

5) <string.h> is required by C99. Remove long-deprecated <strings.h> includes.