remove Go -no-cgo option

It only worked for Go versions before 1.5, which is more than five
years ago and long-unsupported.

Doc/Manual/Go.html

@@ -71,6 +71,7 @@ code.  SWIG fills this gap.
 There are (at least) two different Go compilers.  The first is the gc compiler
 of the <a href="https://golang.org/doc/install">Go distribution</a>, normally
 invoked via the <a href="https://golang.org/cmd/go/">go tool</a>.
+SWIG supports the gc compiler version 1.2 or later.
 The second Go compiler is the <a href="https://golang.org/doc/install/gccgo">
 gccgo compiler</a>, which is a frontend to the GCC compiler suite.
 The interface to C/C++ code is completely different for the two Go compilers.
@@ -142,44 +143,6 @@ You will now have a Go package that you can import from other Go packages as
 usual.
 </p>
 
-<p>
-SWIG can be used without cgo, via the <tt>-no-cgo</tt> option, but
-more steps are required.  This only works with Go versions before 1.5.
-When using Go version 1.2 or later, or when using gccgo, the code
-generated by SWIG can be linked directly into the Go program.  A
-typical command sequence when using the Go compiler of the Go
-distribution would look like this:
-</p>
-
-<div class="code"><pre>
-% swig -go -no-cgo example.i
-% gcc -c code.c    # The C library being wrapped.
-% gcc -c example_wrap.c
-% go tool 6g example.go
-% go tool 6c example_gc.c
-% go tool pack grc example.a example.6 example_gc.6 code.o example_wrap.o
-% go tool 6g main.go
-% go tool 6l main.6
-</pre></div>
-
-<p>
-You can also put the wrapped code into a shared library, and when using the Go
-versions before 1.2 this is the only supported option.  A typical command
-sequence for this approach would look like this:
-</p>
-
-<div class="code"><pre>
-% swig -go -no-cgo -use-shlib example.i
-% gcc -c -fpic example.c
-% gcc -c -fpic example_wrap.c
-% gcc -shared example.o example_wrap.o -o example.so
-% go tool 6g example.go
-% go tool 6c example_gc.c
-% go tool pack grc example.a example.6 example_gc.6
-% go tool 6g main.go  # your code, not generated by SWIG
-% go tool 6l main.6
-</pre></div>
-
 
 <H3><a name="Go_commandline">25.3.1 Go-specific Commandline Options</a></H3>
 
@@ -206,9 +169,7 @@ swig -go -help
 
 <tr>
 <td>-no-cgo</td>
-<td>Generate files that can be used directly, rather than via the Go
-  cgo tool.  This option does not work with Go 1.5 or later.  It is
-  required for versions of Go before 1.2.</td>
+<td>This option is no longer supported.</td>
 </tr>
 
 <tr>
@@ -279,13 +240,10 @@ swig -go -help
 <H3><a name="Go_outputs">25.3.2 Generated Wrapper Files</a></H3>
 
 
-<p>There are two different approaches to generating wrapper files,
-  controlled by SWIG's <tt>-no-cgo</tt> option.  The <tt>-no-cgo</tt>
-  option only works with version of Go before 1.5.  It is required
-  when using versions of Go before 1.2.</p>
-
-<p>With or without the <tt>-no-cgo</tt> option, SWIG will generate the
-  following files when generating wrapper code:</p>
+<p>
+SWIG will generate the following files when generating wrapper
+code:
+</p>
 
 <ul>
 <li>
@@ -308,17 +266,6 @@ or C++ compiler.
 </li>
 </ul>
 
-<p>When the <tt>-no-cgo</tt> option is used, and the <tt>-gccgo</tt>
-  option is not used, SWIG will also generate an additional file:</p>
-
-<ul>
-<li>
-MODULE_gc.c will contain C code which should be compiled with the C
-compiler distributed as part of the gc compiler.  It should then be
-combined with the compiled MODULE.go using go tool pack.
-</li>
-</ul>
-
 
 <H2><a name="Go_basic_tour">25.4 A tour of basic C/C++ wrapping</a></H2>