runtime: teach softfloat interpreter about "add r11, pc, r11"

This is generated during fp code when -shared is active.

Change-Id: Ia1092299b9c3b63ff771ca4842158b42c34bd008
Reviewed-on: https://go-review.googlesource.com/14286Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

src/runtime/softfloat_arm.go

@@ -157,6 +157,17 @@ execute:
 		}
 		return 1
 	}
+	if i == 0xe08fb00b {
+		// add pc to r11
+		// might be part of a PIC floating point move
+		// (or might not, but again no harm done).
+		regs[11] += uint32(uintptr(unsafe.Pointer(pc))) + 8
+
+		if fptrace > 0 {
+			print("*** cpu R[11] += pc ", hex(regs[11]), "\n")
+		}
+		return 1
+	}
 	if i == 0xe08bb00d {
 		// add sp to r11.
 		// might be part of a large stack offset address