[libc] Use a wrapper for rand instead of calling std::rand in fma tests.

libc/test/src/math/FmaTest.h

 //===-- Utility class to test different flavors of fma --------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_LIBC_TEST_SRC_MATH_FMATEST_H
 #define LLVM_LIBC_TEST_SRC_MATH_FMATEST_H
 
 #include "utils/FPUtil/FPBits.h"
 #include "utils/FPUtil/TestHelpers.h"
 #include "utils/MPFRWrapper/MPFRUtils.h"
 #include "utils/UnitTest/Test.h"
-
-#include <random>
+#include "utils/testutils/RandUtils.h"
 
 namespace mpfr = __llvm_libc::testing::mpfr;
 
 template <typename T>
 class FmaTestTemplate : public __llvm_libc::testing::Test {
 private:
   using Func = T (*)(T, T, T);
   using FPBits = __llvm_libc::fputil::FPBits<T>;
   using UIntType = typename FPBits::UIntType;
   const T nan = __llvm_libc::fputil::FPBits<T>::buildNaN(1);
   const T inf = __llvm_libc::fputil::FPBits<T>::inf();
   const T negInf = __llvm_libc::fputil::FPBits<T>::negInf();
   const T zero = __llvm_libc::fputil::FPBits<T>::zero();
   const T negZero = __llvm_libc::fputil::FPBits<T>::negZero();
 
   UIntType getRandomBitPattern() {
     UIntType bits{0};
-    for (size_t i = 0; i < sizeof(UIntType) / 2; ++i) {
-      bits = (bits << 2) + static_cast<uint16_t>(std::rand());
+    for (UIntType i = 0; i < sizeof(UIntType) / 2; ++i) {
+      bits =
+          (bits << 2) + static_cast<uint16_t>(__llvm_libc::testutils::rand());
     }
     return bits;
   }
 
 public:
   void testSpecialNumbers(Func func) {
     EXPECT_FP_EQ(func(zero, zero, zero), zero);
     EXPECT_FP_EQ(func(zero, negZero, negZero), negZero);

libc/utils/testutils/CMakeLists.txt

 if(CMAKE_HOST_UNIX)
   set(EFFile ExecuteFunctionUnix.cpp)
   set(FDReaderFile FDReaderUnix.cpp)
 endif()
 
 add_llvm_library(
   libc_test_utils
+  RandUtils.cpp
+  RandUtils.h
   StreamWrapper.cpp
   StreamWrapper.h
   ${EFFile}
   ExecuteFunction.h
   ${FDReaderFile}
   FDReader.h
 )

libc/utils/testutils/RandUtils.h

+//===-- RandUtils.h ---------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+namespace __llvm_libc {
+namespace testutils {
+
+// Wrapper for std::rand.
+int rand();
+
+} // namespace testutils
+} // namespace __llvm_libc

libc/utils/testutils/RandUtils.cpp

+//===-- RandUtils.cpp -----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "RandUtils.h"
+
+#include <cstdlib>
+
+namespace __llvm_libc {
+namespace testutils {
+
+int rand() { return std::rand(); }
+
+} // namespace testutils
+} // namespace __llvm_libc