Fixes for a clean compilation on ARM

• Move TestVDTMath.cpp to a dedicated directory to avoid warnings for unused sources
• Split function over multiple lines to avoid spurious errors in the nightly builds
• Use portable 8 bit integer types instead of char

Event/EventPacker/include/Event/PackedRichPID.h

@@ -85,7 +85,7 @@ namespace LHCb {
     typedef std::vector<LHCb::PackedRichPID> Vector;
 
     /// Default Packing Version
-    static char defaultPackingVersion() { return 4; }
+    static std::int8_t defaultPackingVersion() { return 4; }
 
     /// Class ID
     static const CLID& classID() { return CLID_PackedRichPIDs; }
@@ -100,7 +100,7 @@ namespace LHCb {
     const Vector& data() const { return m_vect; }
 
     /// Access the packing version
-    [[nodiscard]] char packingVersion() const { return m_packingVersion; }
+    [[nodiscard]] std::int8_t packingVersion() const { return m_packingVersion; }
 
     /// Describe serialization of object
     template <typename T>
@@ -124,7 +124,7 @@ namespace LHCb {
 
   private:
     /// Data packing version
-    char m_packingVersion{defaultPackingVersion()};
+    std::int8_t m_packingVersion{defaultPackingVersion()};
 
     /// The packed data objects
     Vector m_vect;
@@ -173,7 +173,7 @@ namespace LHCb {
     void pack( const Data& pid, PackedData& ppid, PackedDataVector& ppids ) const;
 
     /// Check if the given packing version is supported
-    [[nodiscard]] static bool isSupportedVer( const char ver ) {
+    [[nodiscard]] static bool isSupportedVer( const std::int8_t ver ) {
       const bool OK = ( 0 <= ver && ver <= 4 );
       if ( !OK ) {
         throw GaudiException( fmt::format( "Unknown packed data version {}", (int)ver ), "RichPIDPacker",