TestMathLib: limit libc++ workaround in toDoubleNumber() to MacOS [skip ci]

Author: firewave

test/testmathlib.cpp

@@ -657,7 +657,7 @@ class TestMathLib : public TestFixture {
 
         ASSERT_THROW_INTERNAL_EQUALS(MathLib::toDoubleNumber("invalid"), INTERNAL, "Internal Error. MathLib::toDoubleNumber: conversion failed: invalid");
 
-#ifdef _LIBCPP_VERSION
+#if defined(_LIBCPP_VERSION) && (defined(__APPLE__) && defined(__MACH__))
         ASSERT_THROW_INTERNAL_EQUALS(MathLib::toDoubleNumber("1invalid"), INTERNAL, "Internal Error. MathLib::toDoubleNumber: conversion failed: 1invalid");
         ASSERT_THROW_INTERNAL_EQUALS(MathLib::toDoubleNumber("1.1invalid"), INTERNAL, "Internal Error. MathLib::toDoubleNumber: conversion failed: 1.1invalid");
 #else