[gcc/devel/sphinx] docs: Add missing @headitem for tables.

[Martin Liska <marxin@gcc.gnu.org>]

https://gcc.gnu.org/g:aeed50fedbbf041ae3ebb6d55b2b19992f572366

commit aeed50fedbbf041ae3ebb6d55b2b19992f572366
Author: Martin Liska <mliska@suse.cz>
Date:   Sun Jun 6 17:29:44 2021 +0200

    docs: Add missing @headitem for tables.

Diff:
---
 gcc/doc/extend.texi | 12 ++++++------
 gcc/doc/invoke.texi |  2 +-
 gcc/doc/objc.texi   |  6 +++---
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 8711745bbe8..22f9e93073f 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -15419,7 +15419,7 @@ to make this classification clear at a glance, the arguments and return
 values are given the following pseudo types:
 
 @multitable @columnfractions .20 .30 .15 .35
-@item Pseudo type @tab Real C type @tab Constant? @tab Description
+@headitem Pseudo type @tab Real C type @tab Constant? @tab Description
 @item @code{uh} @tab @code{unsigned short} @tab No @tab an unsigned halfword
 @item @code{uw1} @tab @code{unsigned int} @tab No @tab an unsigned word
 @item @code{sw1} @tab @code{int} @tab No @tab a signed word
@@ -15455,7 +15455,7 @@ for more details.
 The functions listed below map directly to FR-V I-type instructions.
 
 @multitable @columnfractions .45 .32 .23
-@item Function prototype @tab Example usage @tab Assembly output
+@headitem Function prototype @tab Example usage @tab Assembly output
 @item @code{sw1 __ADDSS (sw1, sw1)}
 @tab @code{@var{c} = __ADDSS (@var{a}, @var{b})}
 @tab @code{ADDSS @var{a},@var{b},@var{c}}
@@ -15494,7 +15494,7 @@ The functions listed below map directly to FR-V I-type instructions.
 The functions listed below map directly to FR-V M-type instructions.
 
 @multitable @columnfractions .45 .32 .23
-@item Function prototype @tab Example usage @tab Assembly output
+@headitem Function prototype @tab Example usage @tab Assembly output
 @item @code{uw1 __MABSHS (sw1)}
 @tab @code{@var{b} = __MABSHS (@var{a})}
 @tab @code{MABSHS @var{a},@var{b}}
@@ -15886,7 +15886,7 @@ hardware support exists.  @code{a} and @code{b} are @code{v4i8} values,
 and @code{c} and @code{d} are @code{v2q15} values.
 
 @multitable @columnfractions .50 .50
-@item C code @tab MIPS instruction
+@headitem C code @tab MIPS instruction
 @item @code{a + b} @tab @code{addu.qb}
 @item @code{c + d} @tab @code{addq.ph}
 @item @code{a - b} @tab @code{subu.qb}
@@ -15898,7 +15898,7 @@ hardware support exists for the DSP ASE REV 2.  @code{e} and @code{f} are
 @code{v2i16} values.
 
 @multitable @columnfractions .50 .50
-@item C code @tab MIPS instruction
+@headitem C code @tab MIPS instruction
 @item @code{e * f} @tab @code{mul.ph}
 @end multitable
 
@@ -16284,7 +16284,7 @@ support exists.  @code{a}, @code{b} and @code{c} are @code{v2sf}
 values and @code{x} is an integral value.
 
 @multitable @columnfractions .50 .50
-@item C code @tab MIPS instruction
+@headitem C code @tab MIPS instruction
 @item @code{a + b} @tab @code{add.ps}
 @item @code{a - b} @tab @code{sub.ps}
 @item @code{-a} @tab @code{neg.ps}
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7070b3c64be..d725e764429 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -23565,7 +23565,7 @@ and @samp{cpu32}.  The ColdFire @var{cpu}s are given by the table
 below, which also classifies the CPUs into families:
 
 @multitable @columnfractions 0.20 0.80
-@item @strong{Family} @tab @strong{@samp{-mcpu} arguments}
+@headitem @strong{Family} @tab @strong{@samp{-mcpu} arguments}
 @item @samp{51} @tab @samp{51} @samp{51ac} @samp{51ag} @samp{51cn} @samp{51em} @samp{51je} @samp{51jf} @samp{51jg} @samp{51jm} @samp{51mm} @samp{51qe} @samp{51qm}
 @item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
 @item @samp{5206e} @tab @samp{5206e}
diff --git a/gcc/doc/objc.texi b/gcc/doc/objc.texi
index a8c59429af9..cfd2470bc7a 100644
--- a/gcc/doc/objc.texi
+++ b/gcc/doc/objc.texi
@@ -382,7 +382,7 @@ compiler on an i386 machine:
 @sp 1
 
 @multitable @columnfractions .60 .40
-@item Objective-C type
+@headitem Objective-C type
 @tab Compiler encoding
 @item
 @smallexample
@@ -416,7 +416,7 @@ Objective-C type specifiers:
 @sp 1
 
 @multitable @columnfractions .25 .75
-@item Specifier
+@headitem Specifier
 @tab Encoding
 @item @code{const}
 @tab @code{r}
@@ -445,7 +445,7 @@ Note how @code{const} interacts with pointers:
 @sp 1
 
 @multitable @columnfractions .25 .75
-@item Objective-C type
+@headitem Objective-C type
 @tab Compiler encoding
 @item
 @smallexample