[libc][NFC] Adjust sinf and cosf around -infinity inputs.

The current tests verify if the result of -infinity is a quiet NaN with
sign bit set. But, that need not be the case on all platforms. So, just
checking that the result is a quiet NaN and ignoring the sign bit is
good enough.

libc/test/src/math/cosf_test.cpp

@@ -68,8 +68,8 @@ TEST(CosfTest, SpecialNumbers) {
   EXPECT_EQ(llvmlibc_errno, EDOM);
 
   llvmlibc_errno = 0;
-  EXPECT_TRUE(isNegativeQuietNaN(
-      __llvm_libc::cosf(valueFromBits(BitPatterns::negInf))));
+  EXPECT_TRUE(
+      isQuietNaN(__llvm_libc::cosf(valueFromBits(BitPatterns::negInf))));
   EXPECT_EQ(llvmlibc_errno, EDOM);
 }
 

libc/test/src/math/sinf_test.cpp

@@ -68,8 +68,8 @@ TEST(SinfTest, SpecialNumbers) {
   EXPECT_EQ(llvmlibc_errno, EDOM);
 
   llvmlibc_errno = 0;
-  EXPECT_TRUE(isNegativeQuietNaN(
-      __llvm_libc::sinf(valueFromBits(BitPatterns::negInf))));
+  EXPECT_TRUE(
+      isQuietNaN(__llvm_libc::sinf(valueFromBits(BitPatterns::negInf))));
   EXPECT_EQ(llvmlibc_errno, EDOM);
 }