Final change to make clang build not fail: fxrstor64 and fxsave64

clang is behind the times.

Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>

sys/src/9/amd64/l64fpu.S

@@ -27,12 +27,15 @@ _fninit:
 
 .globl _fxrstor
 _fxrstor:
-	FXRSTOR64 0(%rdi)
+	// Damn. clang lags on assembly, badly.
+	//FXRSTOR64 0(%rdi)
+	.byte 0x48, 0x0f, 0xae, 0x0f //          	fxrstor64 (%rdi)
 	ret
 
 .globl _fxsave
 _fxsave:
-	FXSAVE64 0(%rdi)
+	//FXSAVE64 0(%rdi)
+	.byte 0x48, 0x0f, 0xae, 0x07 //          	fxsave64 (%rdi)
 	ret
 
 .globl _fwait