Extend UNITY_NORETURN mapping for (older) IAR compilers

[rstahn]

#742 introduced a mapping of the define UNITY_NORETURN for different C/C++ standards and specific compilers (GCC, Visual Studio, etc.). This mapping can be extended for IAR compilers which provide a __noreturn keyword. This seems to be supported by IAR compilers for different platforms (ARM, AVR, MSP430), which can be identified by the define __IAR_SYSTEMS_ICC__ providing an indication for the compiler platform version (see also cmake IAR compiler identifcation).

Proposed code extension:

    #elif defined(__IAR_SYSTEMS_ICC__) && (__IAR_SYSTEMS_ICC__ >= 8)
      /* For IAR compilers supporting at least C99 use the IAR specific '__noreturn' keyword */
      /* Based on tests and: */
      /* https://wwwfiles.iar.com/arm/webic/doc/EWARM_DevelopmentGuide.ENU.pdf */
      /* https://wwwfiles.iar.com/AVR/webic/doc/EWAVR_CompilerGuide.pdf */
      /* https://wwwfiles.iar.com/msp430/webic/doc/EW430_CompilerReference.pdf */
      #define UNITY_NORETURN __noreturn

Recent IAR compiler versions support the latest C11/C21 and CPP standards and already use the standard-conform mappings. The addition therefore mainly aims at older compiler versions supporting C99 only.

[mvandervoord]

Thanks for the proposal and the solution, @rstahn !