cmd/go: on arm, all binaries depend on math

Change-Id: I10b781927245a3e9822f9cffe254f226a5b93213
Reviewed-on: https://go-review.googlesource.com/3279Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/go/pkg.go

@@ -524,6 +524,10 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 		if buildRace && (!p.Standard || !raceExclude[p.ImportPath]) {
 			importPaths = append(importPaths, "runtime/race")
 		}
+		// On ARM with GOARM=5, everything depends on math for the link.
+		if p.ImportPath == "main" && goarch == "arm" {
+			importPaths = append(importPaths, "math")
+		}
 	}
 
 	// Build list of full paths to all Go files in the package,