Improve ARM CPU info reporting.

This patch improves several things for Linux/ARM:

- Better detection of the number of CPUs on the target
  device. The content of /proc/cpuinfo only matches the
  number of "online" CPUs, which varies over time with
  recent Android devices.

- Reconstruct the CPUID and ELF hwcaps values from
  /proc/cpuinfo, this is useful to better identify
  target devices in minidumps.

- Make minidump_dump display the new information
  in useful ways.

- Write a small helper class to parse /proc/cpuinfo
  and also use it for x86/64.

- Write a small helper class to parse sysfds cpu lists.

- Add a my_memchr() implementation.

- Add unit tests.

Tested on a Nexus S (1 CPU), Galaxy Nexus (2 CPUs)
and a Nexus 4 (4 CPUs).

Review URL: https://breakpad.appspot.com/540003

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1160 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/linux/linux_libc_support.h

@@ -77,6 +77,8 @@ extern const char* my_read_decimal_ptr(uintptr_t* result, const char* s);
 
 extern void my_memset(void* ip, char c, size_t len);
 
+extern void* my_memchr(const void* src, int c, size_t len);
+
 // The following are considered safe to use in a compromised environment.
 // Besides, this gives the compiler an opportunity to optimize their calls.
 #define my_memcpy  memcpy