go.sys/unix: add asm hooks for solaris to runtime-resident syscall help

also: race is supported on freebsd, so fix a couple of build tags

LGTM=minux
R=rsc, minux
CC=golang-codereviews
https://golang.org/cl/124330043

unix/asm_solaris_amd64.s

@@ -5,3 +5,18 @@
 //
 // System calls for amd64, Solaris are implemented in runtime/syscall_solaris.goc
 //
+
+TEXT ·sysvicall6(SB), 7, $0-64
+	JMP	syscall·sysvicall6(SB)
+
+TEXT ·rawSysvicall6(SB), 7, $0-64
+	JMP	syscall·rawSysvicall6(SB)
+
+TEXT ·dlopen(SB), 7, $0-16
+	JMP	syscall·dlopen(SB)
+
+TEXT ·dlclose(SB), 7, $0-8
+	JMP	syscall·dlclose(SB)
+
+TEXT ·dlsym(SB), 7, $0-16
+	JMP	syscall·dlsym(SB)

unix/race.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin,race linux,race
+// +build darwin,race linux,race freebsd,race
 
 package unix
 

unix/race0.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin,!race dragonfly,!race freebsd linux netbsd openbsd solaris
+// +build darwin,!race linux,!race freebsd,!race netbsd openbsd solaris dragonfly
 
 package unix