[patch, doc] fix some overfull hboxes

[Sandra Loosemore <sandra at codesourcery dot com>]

I've checked in this patch to fix some formatting problems that caused 
overfull hbox (that is, lines that overflow the margin) warnings when 
building the GCC user manual.

This isn't exhaustive -- in particular, I see that the long CPU names in 
the AArch64 and ARM options sections are causing a pile of both 
underfull and overfull hbox warnings.  I think the solution here is to 
format these lists in a more tabular way instead of as flowed text 
(perhaps like @gccoptlist formatting in the "Option Summary" section) 
and do it that way uniformly for all targets that have such lists. 
That's a bigger project which I'll throw back into the pile for now.

-Sandra

2017-12-17  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* doc/extend.texi (x86 Function Attributes): Reformat nocf_check
	example	to avoid overfull hbox.
	* doc/invoke.texi (Option Summary): Add missing @gol.
	(C++ Dialect Options): Reformat -Wnoexcept-type example to avoid 
	overfull hbox.
	

Index: gcc/doc/extend.texi
===================================================================
--- gcc/doc/extend.texi	(revision 255772)
+++ gcc/doc/extend.texi	(working copy)
@@ -5765,21 +5765,27 @@ int foo (void) __attribute__(nocf_check)
 void (*foo1)(void) __attribute__(nocf_check);
 void (*foo2)(void);
 
+/* foo's address is assumed to be valid.  */
 int
-foo (void) /* The function's address is assumed to be valid.  */
+foo (void) 
 
-  /* This call site is not checked for control-flow validity.  */
+  /* This call site is not checked for control-flow 
+     validity.  */
   (*foo1)();
 
-  foo1 = foo2; /* A warning is printed about attribute mismatch.  */
-  /* This call site is still not checked for control-flow validity.  */
+  /* A warning is issued about attribute mismatch.  */
+  foo1 = foo2; 
+
+  /* This call site is still not checked.  */
   (*foo1)();
 
-  /* This call site is checked for control-flow validity.  */
+  /* This call site is checked.  */
   (*foo2)();
 
-  foo2 = foo1; /* A warning is printed about attribute mismatch.  */
-  /* This call site is still checked for control-flow validity.  */
+  /* A warning is issued about attribute mismatch.  */
+  foo2 = foo1; 
+
+  /* This call site is still checked.  */
   (*foo2)();
 
   return 0;
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi	(revision 255773)
+++ gcc/doc/invoke.texi	(working copy)
@@ -549,7 +549,7 @@ Objective-C and Objective-C++ Dialects}.
 -fdisable-tree-@var{pass-name}=@var{range-list} @gol
 -fdump-noaddr  -fdump-unnumbered  -fdump-unnumbered-links @gol
 -fdump-class-hierarchy@r{[}-@var{n}@r{]} @gol
--fdump-final-insns@r{[}=@var{file}@r{]}
+-fdump-final-insns@r{[}=@var{file}@r{]} @gol
 -fdump-ipa-all  -fdump-ipa-cgraph  -fdump-ipa-inline @gol
 -fdump-lang-all @gol
 -fdump-lang-@var{switch} @gol
@@ -2935,12 +2935,18 @@ Warn if the C++17 feature making @code{n
 type changes the mangled name of a symbol relative to C++14.  Enabled
 by @option{-Wabi} and @option{-Wc++17-compat}.
 
+As an example:
+
 @smallexample
 template <class T> void f(T t) @{ t(); @};
 void g() noexcept;
-void h() @{ f(g); @} // in C++14 calls f<void(*)()>, in C++17 calls f<void(*)()noexcept>
+void h() @{ f(g); @} 
 @end smallexample
 
+@noindent
+In C++14, @code{f} calls calls @code{f<void(*)()>}, but in
+C++17 it calls @code{f<void(*)()noexcept>}.
+
 @item -Wclass-memaccess @r{(C++ and Objective-C++ only)}
 @opindex Wclass-memaccess
 Warn when the destination of a call to a raw memory function such as