code review 35990043: runtime: add support for GOOS=solaris

src/pkg/runtime/sys_solaris_amd64.s

 // Copyright 2013 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 //
 // System calls and other sys.stuff for AMD64, SunOS
 // /usr/include/sys/syscall.h for syscall numbers.
 //
 
 #include "zasm_GOOS_GOARCH.h"
 #include "../../cmd/ld/textflag.h"
@@ skipping 59 matching lines @@
         PUSHQ   DI                      // save for later
         MOVQ    libcall_fn(DI), AX
         MOVQ    libcall_args(DI), R11
         MOVQ    libcall_n(DI), R10
 
         get_tls(CX)
         MOVQ    m(CX), BX
         MOVQ    m_perrno(BX), DX
         CMPQ    DX, $0
         JEQ     skiperrno1
-        MOVL    $0,     0(DX)
+        MOVL    $0, 0(DX)
 
 skiperrno1:
         CMPQ    R11, $0
         JEQ     skipargs
         // Load 6 args into correspondent registers.
         MOVQ    0(R11), DI
         MOVQ    8(R11), SI
         MOVQ    16(R11), DX
         MOVQ    24(R11), CX
         MOVQ    32(R11), R8
         MOVQ    40(R11), R9
 skipargs:
 
         // Call SysV function
         CALL    AX
 
         // Return result
         POPQ    DI
         MOVQ    AX, libcall_r1(DI)
         MOVQ    DX, libcall_r2(DI)
 
         get_tls(CX)
         MOVQ    m(CX), BX
         MOVQ    m_perrno(BX), AX
         CMPQ    AX, $0
         JEQ     skiperrno2
         MOVL    0(AX), AX
         MOVQ    AX, libcall_err(DI)

[gusev.vitaliy, 2018/03/01 17:23:13]

Why here is used errno as indicator of error from system call ? Why don't use AX
value from line 99  and check it on "-1" ? 

POSIX and man pages  says that errno value makes sense only when sys call return
error, but not vice versa. Of course I see errno resetting on the line 80.

 
 skiperrno2:·····
         RET
 
 // uint32 tstart_sysvicall(M *newm);
 TEXT runtime·tstart_sysvicall(SB),NOSPLIT,$0
         // DI contains first arg newm
         MOVQ    m_g0(DI), DX            // g
 
         // Make TLS entries point at g and m.
@@ skipping 139 matching lines @@
         // restore registers
         MOVQ    32(SP), BX
         MOVQ    40(SP), BP
         MOVQ    48(SP), R12
         MOVQ    56(SP), R13
         MOVQ    64(SP), R14
         MOVQ    72(SP), R15
 
         ADDQ    $184, SP
         RET