title: Predefined macro to distinguish arm-none-eabi-gcc from gcc
body: <p>I am building my own library which is supposed to work both on an arm mbed and on linux platforms. If the target is ARM mbed, then the library needs to be cross-compiled with <code>arm-none-eabi-gcc</code> while if the target platform is linux, the library needs to be compiled with <code>gcc</code>. Is there a predefined compiler macro that will allow me to determine which compiler was invoked to compile the library? Note that Raspberry Pi which 
  has an ARM CPU also needs to be supported so I cannot use any arch macros.</p>