Dup to fcntl (#3047)

* Adding restrict_platform support for FPRIME_HAS_XYZ flags

* fcntl here is the equivalent of dup. Using fcntl because it's supported in VxWorks too

* Undoing regression

---------

Co-authored-by: Michael D Starch <Michael.D.Starch@jpl.nasa.gov>
Co-authored-by: M Starch <LeStarch@googlemail.com>

Os/Posix/File.cpp

@@ -45,21 +45,17 @@ static_assert(std::numeric_limits<FwSignedSizeType>::min() <= std::numeric_limit
               "Minimum value of FwSizeType larger than the minimum value of ssize_t. Configure a larger type.");
 
 //!\brief default copy constructor
-#ifndef TGT_OS_TYPE_VXWORKS
 PosixFile::PosixFile(const PosixFile& other) {
     // Must properly duplicate the file handle
-    this->m_handle.m_file_descriptor = ::dup(other.m_handle.m_file_descriptor);
+    this->m_handle.m_file_descriptor = fcntl(other.m_handle.m_file_descriptor, F_DUPFD, 0);
 }
-#endif
 
-#ifndef TGT_OS_TYPE_VXWORKS
 PosixFile& PosixFile::operator=(const PosixFile& other) {
     if (this != &other) {
-        this->m_handle.m_file_descriptor = ::dup(other.m_handle.m_file_descriptor);
+        this->m_handle.m_file_descriptor = fcntl(other.m_handle.m_file_descriptor, F_DUPFD, 0);
     }
     return *this;
 }
-#endif
 
 PosixFile::Status PosixFile::open(const char* filepath,
                                   PosixFile::Mode requested_mode,

Os/Posix/File.hpp

@@ -33,24 +33,10 @@ class PosixFile : public FileInterface {
     PosixFile() = default;
 
     //! \brief copy constructor
-#ifdef TGT_OS_TYPE_VXWORKS
-    // Adding this pound-if-define code to allow building VxWorks for POSIX.
-    // Better than the alternative of copying this entire file to the VxWorks repo
-    // and removing this line.
-    PosixFile(const PosixFile& other) = delete;
-#else
     PosixFile(const PosixFile& other);
-#endif
-
-//! \brief assignment operator that copies the internal representation
-#ifdef TGT_OS_TYPE_VXWORKS
-    // Adding this pound-if-define code to allow building VxWorks for POSIX.
-    // Better than the alternative of copying this entire file to the VxWorks repo
-    // and removing this line.
-    PosixFile& operator=(const PosixFile& other) = delete;
-#else
+
+    //! \brief assignment operator that copies the internal representation
     PosixFile& operator=(const PosixFile& other);
-#endif
 
     //! \brief destructor
     //!