Are you sure that make file generated that error? CC is defined as g++, but the error is that G++ doesn't exist. Solaris is case sensitive, so the error suggests you're not using the makefile posted.
Does the G++ command work from the command line (also, does the same command work if you use g++ instead of G++)?

Is the makefile you posted called Makefile (note the case) or something else? If something else then you need to specify the makefile name with -f (e.g. if it's called, the command is make -f

What command caused the Error code 127?