runtime: fix typo in comment

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/125500043

src/pkg/runtime/asm_386.s

@@ -1167,7 +1167,7 @@ TEXT runtime·memeq(SB),NOSPLIT,$0-13
 
 // eqstring tests whether two strings are equal.
 // See runtime_test.go:eqstring_generic for
-// equivlaent Go code.
+// equivalent Go code.
 TEXT runtime·eqstring(SB),NOSPLIT,$0-17
 	MOVL	s1len+4(FP), AX
 	MOVL	s2len+12(FP), BX

src/pkg/runtime/asm_amd64.s

@@ -1140,7 +1140,7 @@ TEXT runtime·memeq(SB),NOSPLIT,$0-25
 
 // eqstring tests whether two strings are equal.
 // See runtime_test.go:eqstring_generic for
-// equivlaent Go code.
+// equivalent Go code.
 TEXT runtime·eqstring(SB),NOSPLIT,$0-33
 	MOVQ	s1len+8(FP), AX
 	MOVQ	s2len+24(FP), BX

src/pkg/runtime/asm_amd64p32.s

@@ -785,7 +785,7 @@ TEXT runtime·memeq(SB),NOSPLIT,$0-17
 
 // eqstring tests whether two strings are equal.
 // See runtime_test.go:eqstring_generic for
-// equivlaent Go code.
+// equivalent Go code.
 TEXT runtime·eqstring(SB),NOSPLIT,$0-17
 	MOVL	s1len+4(FP), AX
 	MOVL	s2len+12(FP), BX

src/pkg/runtime/asm_arm.s

@@ -724,7 +724,7 @@ _next2:
 
 // eqstring tests whether two strings are equal.
 // See runtime_test.go:eqstring_generic for
-// equivlaent Go code.
+// equivalent Go code.
 TEXT runtime·eqstring(SB),NOSPLIT,$-4-17
 	MOVW	s1len+4(FP), R0
 	MOVW	s2len+12(FP), R1