Changes to facilitate platform independence.
Ben Avison authored
Detail:
 CApp:
  * New variable CLEAN_DEPEND is now the preferred way to specify additional
    clean actions because GNU make doesn't have an equivalent to amu's :: rules
  * Can now indicate preference to use C++ linker options using LINK_TYPE
  * Gains install phase support:
    + INSTALLAPPFILES lists the files to be copied, effectively specified
      relative to LocalRes$Path
    + Adopted INSTTYPE concept from DDE makefiles for cases where executable
      and support files need to be installed to different locations
    + Unusual cases can override this implementation using CUSTOMINSTALLAPP
      and/or CUSTOMINSTALLTOOL

  CLibrary:
  * New variable CLEAN_DEPEND is now the preferred way to specify additional
    clean actions because GNU make doesn't have an equivalent to amu's :: rules
  * -o is no longer a mandatory argument to libfile - now in ARFLAGS rather
    than used explicitly

  DbgRules / StdRules:
  * Macroised some Norcroft-specific features

  HostTools:
  * Clean phase support was incomplete

  StdTools:
  * A few additional tool definitions
  * Added macro definitions for common C options
  * C's enable-warnings and suppress-function-name-embedding options now on by
    default because they're usually (maybe even universally?) used - it won't
    hurt if they're specified again by existing makefiles
  * C++ now has equivalent INCLUDES and DEFINES variables, and the standard C++
    headers are on the default include path
  * SEP is defined as the directory separator character and can be used from
    top-level makefiles in a platform-independent way

  Functionally equivalent versions of the following makefile fragments
  have been developed so far for executing on a Posix build host:
    AppLibs, CApp, CLibrary, DbgRules, HostTools, StdRules, StdTools
  These suport native compilers (when APCS=Host) and cross-compilers,
  and GCC (when TOOLCHAIN=GNU) and Norcroft toolchains - typically these
  environment variables would be selected by running an Env file.

Admin:
  Tested by building as many as possible of the DDE components on RISC OS
  and on Linux, using native and cross compilers, and using Norcroft and
  GNU toolchains.

Version 5.01. Tagged as 'BuildSys-5_01'
4477e695