libc -- Remove assembler i386 strlen() routine.

libc -- Remove assembler i386 strlen() routine.

On a number of processors, it is slower than the obvious C version.
(400,000,000 loops, times in sec)

On a 2.66 GHz Core 2:
                asm     C
10-by string    22.9    9.5
68-by string    77.2    19.8
175-by string   173.7   40.6

On a 2.0 GHz Athlon64 3000+:
                asm     C
10-by string    11.3    9.9
68-by string    34.7    34.7
175-by string   78.7    77.6

On a 2.2 GHz Core i7 (nehalem):
                asm     C
10-by string    13.4    5.2
68-by string    33.8    29.5
175-by string   71.6    67.4