Use std:: on symbols declared in C++-style C headers.

src/arm/codegen-arm.cc

Index: src/arm/codegen-arm.cc
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index b044ca9b30250c03b805d5fde1a3c52f8590c90d..c398a1b71d1f38eb13f193fc023f25ea0874f7b3 100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -50,10 +50,10 @@ double fast_exp_simulator(double x) {
 
 
 UnaryMathFunction CreateExpFunction() {
-  if (!FLAG_fast_math) return &exp;
+  if (!FLAG_fast_math) return &std::exp;
   size_t actual_size;
   byte* buffer = static_cast<byte*>(OS::Allocate(1 * KB, &actual_size, true));
-  if (buffer == NULL) return &exp;
+  if (buffer == NULL) return &std::exp;
   ExternalReference::InitializeMathExpData();
 
   MacroAssembler masm(NULL, buffer, static_cast<int>(actual_size));
@@ -351,7 +351,7 @@ OS::MemCopyUint16Uint8Function CreateMemCopyUint16Uint8Function(
 
 
 UnaryMathFunction CreateSqrtFunction() {
-  return &sqrt;
+  return &std::sqrt;
 }