gotools/go/internal/cgo/cgo_pkgconfig.go

// pkgConfig runs pkg-config with the specified arguments and returns the flags it prints.
func pkgConfig(mode string, pkgs []string) (flags []string, err error) { … }

// pkgConfigFlags calls pkg-config if needed and returns the cflags
// needed to build the package.
func pkgConfigFlags(p *build.Package) (cflags []string, err error) { … }