cmd/go: recognize AIX objects and archives

Reviewed-on: https://go-review.googlesource.com/88275

From-SVN: r256873

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-6b4f1391e2cd637fa5ed797bb3ab43d9ede61997
+cf33aedb66b5121708f5640443c1336080a47fe5
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/cmd/go/internal/work/exec.go

@@ -1282,6 +1282,7 @@ func (b *Builder) cover(a *Action, dst, src string, perm os.FileMode, varName st
 
 var objectMagic = [][]byte{
 	{'!', '<', 'a', 'r', 'c', 'h', '>', '\n'}, // Package archive
+	{'<', 'b', 'i', 'g', 'a', 'f', '>', '\n'}, // Package AIX big archive
 	{'\x7F', 'E', 'L', 'F'},                   // ELF
 	{0xFE, 0xED, 0xFA, 0xCE},                  // Mach-O big-endian 32-bit
 	{0xFE, 0xED, 0xFA, 0xCF},                  // Mach-O big-endian 64-bit
@@ -1291,6 +1292,8 @@ var objectMagic = [][]byte{
 	{0x00, 0x00, 0x01, 0xEB},                  // Plan 9 i386
 	{0x00, 0x00, 0x8a, 0x97},                  // Plan 9 amd64
 	{0x00, 0x00, 0x06, 0x47},                  // Plan 9 arm
+	{0x01, 0xDF},                              // XCOFF32
+	{0x01, 0xF7},                              // XCOFF64
 }
 
 func isObject(s string) bool {