lex and bison aren't needed to build llvm anymore.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61560 91177308-0d34-0410-b5e6-96231b3b80d8

docs/MakefileGuide.html

@@ -781,8 +781,6 @@
   <dl>
     <dt><a name="AR"><tt>AR</tt></a> <small>(defaulted)</small></dt>
     <dd>Specifies the path to the <tt>ar</tt> tool.</dd>
-    <dt><a name="BISON"><tt>BISON</tt></a><small>(configured)</small></dt>
-    <dd>Specifies the path to the <tt>bison</tt> tool.</dd>
     <dt><a name="PROJ_OBJ_DIR"><tt>PROJ_OBJ_DIR</tt></a></dt>
     <dd>The directory into which the products of build rules will be placed.
     This might be the same as 
@@ -812,8 +810,6 @@
     <dd>Provides the extension to be used on executables built by the makefiles.
     The value may be empty on platforms that do not use file extensions for
     executables (e.g. Unix).</dd>
-    <dt><a name="FLEX"><tt>FLEX</tt></a><small>(configured)</small></dt>
-    <dd>Specifies the path to the <tt>flex</tt> tool.</dd>
     <dt><a name="INSTALL"><tt>INSTALL</tt></a><small>(configured)</small></dt>
     <dd>Specifies the path to the <tt>install</tt> tool.</dd>
     <dt><a name="LDFLAGS"><tt>LDFLAGS</tt></a><small>(configured)</small></dt>
@@ -981,8 +977,6 @@
     INCFiles
     InternalTargets
     LD.Flags
-    LexFiles
-    LexOutput
     LibName.A
     LibName.BC
     LibName.LA
@@ -1020,8 +1014,6 @@
     ToolBuildPath
     TopLevelTargets
     UserTargets
-    YaccFiles
-    YaccOutput
   </tt></p>
 </div>