Strip single-predicate any/all instead of extracting

Rather than extracting every any/all into their own classifications,
eliminate them (and replace them with their body) if they contain only one
predicate.  This is most likely to happen after template expansion, and
there were an alarming number of them in our system.

Stripping them out of one of our programs saved ~0.2MiB of output, and
removed many intermediate classifications.  It removed ~1,075 lines, which
should correspond closely to the actual number of classifications.

Discovering this required stripping the template barriers, which was done in
a previous commit.

Unfortunately, the performance improvement from this wasn't significantly,
largely because of the nondeterminisim of GC, which can easily mask the
gains.  But a new line `v8::internal::FixedArray::set(int,
v8::internal::Object)` appeared in the profiler output, making me wonder
whether the JIT is starting to understand more interesting properties of the
system.

`mprotect` and `v8::internal::heap_internals::GenerationalBarrier` also
appeared, which are related to GC.

src/current/include/preproc/macros.xsl

@@ -304,10 +304,13 @@
 </template>
 
 
-<template mode="preproc:class-groupgen" priority="9"
-    match="lv:any[ not( element() ) ]
-           |lv:all[ not( element() ) ]">
-  <!-- useless; remove -->
+<!--
+  Not only should we not generate a group for single-predicate any/all, but
+  we should remove it entirely.
+-->
+<template mode="preproc:class-groupgen" priority="7"
+    match="(lv:any|lv:all)[ count( lv:* ) lt 2 ]">
+  <apply-templates mode="preproc:class-groupgen" />
 </template>