Compile with GNU99 mode to prevent warnings on str[n]dup

Prior, the compilation resulted in the warning of

 cc -O3 -Wall    make2graph.c   -o make2graph
 make2graph.c: In function ‘targetName’:
 make2graph.c:131: warning: implicit declaration of function ‘strndup’
 make2graph.c:131: warning: incompatible implicit declaration of built-in function ‘strndup’

Solution was found here: http://stackoverflow.com/questions/9168150/implicit-declaration-of-strndup
Do not add the makefile itself to the targets

Simply start the parsing of the dependency tree later