Improve QNX support

This cherry-picks the source changes from PR made by @pkleymonov-qnx,
without including the build path changes that are irrelevant unless
we can add a QNX target to our CI.

Close #2953

src/catch2/internal/catch_console_colour.cpp

@@ -161,7 +161,11 @@ namespace {
 #endif // Windows/ ANSI/ None
 
 
-#if defined( CATCH_PLATFORM_LINUX ) || defined( CATCH_PLATFORM_MAC ) || defined( __GLIBC__ ) || defined(__FreeBSD__)
+#if defined( CATCH_PLATFORM_LINUX ) \
+ || defined( CATCH_PLATFORM_MAC ) \
+ || defined( __GLIBC__ ) \
+ || defined( __FreeBSD__ ) \
+ || defined( CATCH_PLATFORM_QNX )
 #    define CATCH_INTERNAL_HAS_ISATTY
 #    include <unistd.h>
 #endif

src/catch2/internal/catch_debugger.cpp

@@ -69,7 +69,7 @@
         #endif
     } // namespace Catch
 
-#elif defined(CATCH_PLATFORM_LINUX)
+#elif defined(CATCH_PLATFORM_LINUX) || defined(CATCH_PLATFORM_QNX)
     #include <fstream>
     #include <string>
 

src/catch2/internal/catch_debugger.hpp

@@ -49,7 +49,7 @@ namespace Catch {
         #define CATCH_TRAP()  __asm__(".inst 0xde01")
     #endif
 
-#elif defined(CATCH_PLATFORM_LINUX)
+#elif defined(CATCH_PLATFORM_LINUX) || defined(CATCH_PLATFORM_QNX)
     // If we can use inline assembler, do it because this allows us to break
     // directly at the location of the failing check instead of breaking inside
     // raise() called from it, i.e. one stack frame below.

src/catch2/internal/catch_platform.hpp

@@ -25,6 +25,9 @@
 #elif defined(linux) || defined(__linux) || defined(__linux__)
 #  define CATCH_PLATFORM_LINUX
 
+#elif defined(__QNX__)
+#  define CATCH_PLATFORM_QNX
+
 #elif defined(WIN32) || defined(__WIN32__) || defined(_WIN32) || defined(_MSC_VER) || defined(__MINGW32__)
 #  define CATCH_PLATFORM_WINDOWS