[compiler-rt] Add support for big endian for Arm's __negdf2vfp (llvm#127096)

In soft floating-point ABI, this function takes the double argument as a
pair of registers r0 and r1.

The ordering of these two registers follow the endianness rules,
therefore the register on which the bit flipping must happen depends on
the endianness.

Author: vhscampos

compiler-rt/lib/builtins/arm/negdf2vfp.S

@@ -20,7 +20,11 @@ DEFINE_COMPILERRT_FUNCTION(__negdf2vfp)
 #if defined(COMPILER_RT_ARMHF_TARGET)
 	vneg.f64 d0, d0
 #else
-	eor	r1, r1, #-2147483648	// flip sign bit on double in r0/r1 pair
+#if _YUGA_BIG_ENDIAN
+	eor	r0, r0, #0x80000000	// flip sign bit on double in r0/r1 pair
+#else
+	eor	r1, r1, #0x80000000	// flip sign bit on double in r0/r1 pair
+#endif
 #endif
 	bx	lr
 END_COMPILERRT_FUNCTION(__negdf2vfp)