Make arch-specific constants dependent on sys.info().machine

Values such as socket constants and types are arch-specific and can
only be resolved at runtime.

Patch by RT-RK.

BUG= #496
TEST= ninja -C out/DebugXMIPS
R=erikcorry@google.com

Review URL: https://codereview.chromium.org/2203023002 .

Patch from "RT-RK" <petarj@mips.com>.

pkg/os/lib/src/errno.dart

@@ -101,8 +101,9 @@ abstract class _PosixErrnos extends Errnos {
 }
 
 class _LinuxErrnos extends _PosixErrnos {
-  int get EADDRNOTAVAIL => 99;
-  int get EINPROGRESS => 115;
+  static final bool isMips = sys.info().machine == 'mips';
+  int get EADDRNOTAVAIL => isMips ? 126 : 99;
+  int get EINPROGRESS => isMips ? 150 : 115;
 }
 
 class _MacOSErrnos extends _PosixErrnos {

pkg/os/lib/src/system_linux.dart

@@ -10,19 +10,21 @@ class LinuxSystem extends PosixSystem {
   static final ForeignFunction _openLinux =
       ForeignLibrary.main.lookup("open64");
 
+  static final bool isMips = sys.info().machine == 'mips';
+
   int get AF_INET6 => 10;
 
-  int get O_CREAT => 64;
+  int get O_CREAT => isMips ? 256 : 64;
   int get O_TRUNC => 512;
-  int get O_APPEND => 1024;
-  int get O_NONBLOCK => 2048;
+  int get O_APPEND => isMips ? 8 : 1024;
+  int get O_NONBLOCK => isMips ? 128 : 2048;
   int get O_CLOEXEC => 524288;
 
-  int get FIONREAD => 0x541B;
+  int get FIONREAD => isMips ? 0x467f : 0x541b;
 
-  int get SOL_SOCKET => 1;
+  int get SOL_SOCKET => isMips ? 65535 : 1;
 
-  int get SO_REUSEADDR => 2;
+  int get SO_REUSEADDR => isMips ? 4 : 2;
 
   // The size of fields and the struct used by uname.
   // From /usr/include/sys/utsname.h

pkg/os/lib/src/system_posix.dart

@@ -59,11 +59,13 @@ abstract class PosixSystem implements System {
   static final ForeignFunction _uname =
       ForeignLibrary.main.lookup("uname");
 
+  static final bool isMips = sys.info().machine == 'mips';
+
   int get AF_INET => 2;
   int get AF_INET6;
 
-  int get SOCK_STREAM => 1;
-  int get SOCK_DGRAM => 2;
+  int get SOCK_STREAM => isMips ? 2 : 1;
+  int get SOCK_DGRAM => isMips ? 1 : 2;
 
   int get O_RDONLY => 0;
   int get O_WRONLY => 1;