linux-user: Fix /proc/cpuinfo output for hppa

linux-user: Fix /proc/cpuinfo output for hppa

The hppa architectures provides an own output for the emulated
/proc/cpuinfo file.

Some userspace applications count (even if that's not the recommended
way) the number of lines which start with "processor:" and assume that
this number then reflects the number of online CPUs. Since those 3
architectures don't provide any such line, applications may assume "0"
CPUs.  One such issue can be seen in debian bug report:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1024653

Avoid such issues by adding a "processor:" line for each of the online
CPUs.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <Y9QvyRSq1I1k5/JW@p100>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>