runtime: clean up libc_* definitions on Solaris

All functions defined in syscall2_solaris.go have the respective libc_*
var in syscall_solaris.go, except for libc_close. Move it from
os3_solaris.go

Remove unused libc_fstat.

Order go:cgo_import_dynamic and go:linkname lists in
syscall2_solaris.go alphabetically.

Change-Id: I9f12fa473cf1ae351448ac45597c82a67d799c31
Reviewed-on: https://go-review.googlesource.com/97736Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/runtime/os3_solaris.go

@@ -12,9 +12,7 @@ import "unsafe"
 
 //go:cgo_import_dynamic libc____errno ___errno "libc.so"
 //go:cgo_import_dynamic libc_clock_gettime clock_gettime "libc.so"
-//go:cgo_import_dynamic libc_close close "libc.so"
 //go:cgo_import_dynamic libc_exit exit "libc.so"
-//go:cgo_import_dynamic libc_fstat fstat "libc.so"
 //go:cgo_import_dynamic libc_getcontext getcontext "libc.so"
 //go:cgo_import_dynamic libc_kill kill "libc.so"
 //go:cgo_import_dynamic libc_madvise madvise "libc.so"
@@ -46,9 +44,7 @@ import "unsafe"
 
 //go:linkname libc____errno libc____errno
 //go:linkname libc_clock_gettime libc_clock_gettime
-//go:linkname libc_close libc_close
 //go:linkname libc_exit libc_exit
-//go:linkname libc_fstat libc_fstat
 //go:linkname libc_getcontext libc_getcontext
 //go:linkname libc_kill libc_kill
 //go:linkname libc_madvise libc_madvise
@@ -81,9 +77,7 @@ import "unsafe"
 var (
 	libc____errno,
 	libc_clock_gettime,
-	libc_close,
 	libc_exit,
-	libc_fstat,
 	libc_getcontext,
 	libc_kill,
 	libc_madvise,

src/runtime/syscall2_solaris.go

@@ -11,6 +11,7 @@ import _ "unsafe" // for go:linkname
 //go:cgo_import_dynamic libc_close close "libc.so"
 //go:cgo_import_dynamic libc_execve execve "libc.so"
 //go:cgo_import_dynamic libc_fcntl fcntl "libc.so"
+//go:cgo_import_dynamic libc_forkx forkx "libc.so"
 //go:cgo_import_dynamic libc_gethostname gethostname "libc.so"
 //go:cgo_import_dynamic libc_getpid getpid "libc.so"
 //go:cgo_import_dynamic libc_ioctl ioctl "libc.so"
@@ -21,7 +22,6 @@ import _ "unsafe" // for go:linkname
 //go:cgo_import_dynamic libc_setuid setuid "libc.so"
 //go:cgo_import_dynamic libc_setpgid setpgid "libc.so"
 //go:cgo_import_dynamic libc_syscall syscall "libc.so"
-//go:cgo_import_dynamic libc_forkx forkx "libc.so"
 //go:cgo_import_dynamic libc_wait4 wait4 "libc.so"
 
 //go:linkname libc_chdir libc_chdir
@@ -29,6 +29,7 @@ import _ "unsafe" // for go:linkname
 //go:linkname libc_close libc_close
 //go:linkname libc_execve libc_execve
 //go:linkname libc_fcntl libc_fcntl
+//go:linkname libc_forkx libc_forkx
 //go:linkname libc_gethostname libc_gethostname
 //go:linkname libc_getpid libc_getpid
 //go:linkname libc_ioctl libc_ioctl
@@ -39,5 +40,4 @@ import _ "unsafe" // for go:linkname
 //go:linkname libc_setuid libc_setuid
 //go:linkname libc_setpgid libc_setpgid
 //go:linkname libc_syscall libc_syscall
-//go:linkname libc_forkx libc_forkx
 //go:linkname libc_wait4 libc_wait4

src/runtime/syscall_solaris.go

@@ -9,6 +9,7 @@ import "unsafe"
 var (
 	libc_chdir,
 	libc_chroot,
+	libc_close,
 	libc_execve,
 	libc_fcntl,
 	libc_forkx,