code review 4550084: cgo: support pkg-config for flags and libs

src/cmd/cgo/doc.go

 // Copyright 2009 The Go Authors.  All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 /*
 
 Cgo enables the creation of Go packages that call C code.
 
 Usage: cgo [compiler options] file.go
 
@@ skipping 18 matching lines @@
 by $GOOS, $GOARCH, or $GOOS/$GOARCH are only defined in matching
 systems.  For example:
 
         // #cgo CFLAGS: -DPNG_DEBUG=1
         // #cgo linux CFLAGS: -DLINUX=1
         // #cgo LDFLAGS: -lpng
         // #include <png.h>
         import "C"
 
 Alternatively, CFLAGS and LDFLAGS may be obtained via the pkg-config
-tool using a #cgo directive with the package names:

[adg, 2011/05/26 22:43:02]

tool using a '#cgo pkg-config:' directive followed by the package names.
For example:

+tool using a '#cgo pkg-config:' directive followed by the package names.
+For example:
 
         // #cgo pkg-config: png cairo
         // #include <png.h>
         import "C"
 
 Within the Go file, C identifiers or field names that are keywords in Go
 can be accessed by prefixing them with an underscore: if x points at a C
 struct with a field named "type", x._type accesses the field.
 
 The standard C numeric types are available under the names
@@ skipping 20 matching lines @@
 Cgo transforms the input file into four output files: two Go source
 files, a C file for 6c (or 8c or 5c), and a C file for gcc.
 
 The standard package makefile rules in Make.pkg automate the
 process of using cgo.  See $GOROOT/misc/cgo/stdio and
 $GOROOT/misc/cgo/gmp for examples.
 
 Cgo does not yet work with gccgo.
 */
 package documentation