gcc -std=gnu11 -o testptr   `pkg-config --libs dbus-1 json-c gtk+-3.0` 
Package dbus-1 was not found in the pkg-config search path.
Perhaps you should add the directory containing `dbus-1.pc'
to the PKG_CONFIG_PATH environment variable
Package 'dbus-1', required by 'virtual:world', not found
Package 'json-c', required by 'virtual:world', not found
Package 'gtk+-3.0', required by 'virtual:world', not found
gcc: fatal error: no input files
compilation terminated.
make: *** [Makefile:69: testptr] Error 1