Adjust floating-point nextUp test for NaN on ARM

Author: xwu

Diff for: test/stdlib/FloatingPoint.swift.gyb

@@ -574,21 +574,16 @@ FloatingPoint.test("Double.nextUp, .nextDown")
   expectBitwiseEqual(-prev, (-succ).nextUp)
 }
 
-// FIXME: This test is failing on armv4: SR-7159
-#if arch(i386) || arch(x86_64)
-
 %for Self in ['Float', 'Double']:
 FloatingPoint.test("${Self}.nextUp, .nextDown/nan") {
   let x = ${Self}.nan
-  expectBitwiseEqual(x, x.nextUp)
-  expectBitwiseEqual(x, x.nextDown)
+  expectTrue(x.nextUp.isNaN)
+  expectTrue(x.nextDown.isNaN)
   expectTrue((-x).nextDown.isNaN)
   expectTrue((-x).nextUp.isNaN)
 }
 %end
 
-#endif
-
 #if arch(i386) || arch(x86_64)
 
 FloatingPoint.test("Float80/ExpressibleByIntegerLiteral") {