Remove --with-lg-size-class-group.

Four size classes per size doubling has proven to be a universally good
choice for the entire 4.x release series, so there's little point to
preserving this configurability.

This partially resolves #580.

INSTALL

@@ -220,35 +220,6 @@ any of the following arguments (not a definitive list) to 'configure':
     when cross compiling, or when overriding the default for systems that do
     not explicitly support huge pages.
 
---with-lg-size-class-group=<lg-size-class-group>
-    Specify the base 2 log of how many size classes to use for each doubling in
-    size.  By default jemalloc uses <lg-size-class-group>=2, which results in
-    e.g. the following size classes:
-
-      [...], 64,
-      80, 96, 112, 128,
-      160, [...]
-
-    <lg-size-class-group>=3 results in e.g. the following size classes:
-
-      [...], 64,
-      72, 80, 88, 96, 104, 112, 120, 128,
-      144, [...]
-
-    The minimal <lg-size-class-group>=0 causes jemalloc to only provide size
-    classes that are powers of 2:
-
-      [...],
-      64,
-      128,
-      256,
-      [...]
-
-    An implementation detail currently limits the total number of small size
-    classes to 255, and a compilation error will result if the
-    <lg-size-class-group> you specify cannot be supported.  The limit is
-    roughly <lg-size-class-group>=4, depending on page size.
-
 --with-lg-quantum=<lg-quantum>
     Specify the base 2 log of the minimum allocation alignment.  jemalloc needs
     to know the minimum alignment that meets the following C standard
@@ -272,8 +243,7 @@ any of the following arguments (not a definitive list) to 'configure':
     this allocator noncompliance means that it is generally safe in practice to
     let jemalloc's minimum alignment follow glibc's lead.  If you specify
     --with-lg-quantum=3 during configuration, jemalloc will provide additional
-    size classes that are not 16-byte-aligned (24, 40, and 56, assuming
+    size classes that are not 16-byte-aligned (24, 40, and 56).
-    --with-lg-size-class-group=2).
 
 --with-lg-tiny-min=<lg-tiny-min>
     Specify the base 2 log of the minimum tiny size class to support.  Tiny

configure.ac

@@ -1401,12 +1401,6 @@ AC_ARG_WITH([lg_page_sizes],
    [Base 2 logs of system page sizes to support])],
   [LG_PAGE_SIZES="$with_lg_page_sizes"], [LG_PAGE_SIZES="$LG_PAGE"])
 
-AC_ARG_WITH([lg_size_class_group],
-  [AS_HELP_STRING([--with-lg-size-class-group=<lg-size-class-group>],
-   [Base 2 log of size classes per doubling])],
-  [LG_SIZE_CLASS_GROUP="$with_lg_size_class_group"],
-  [LG_SIZE_CLASS_GROUP="2"])
-
 dnl ============================================================================
 dnl jemalloc configuration.
 dnl 
@@ -2022,7 +2016,7 @@ AC_CONFIG_COMMANDS([include/jemalloc/internal/public_unnamespace.h], [
 ])
 AC_CONFIG_COMMANDS([include/jemalloc/internal/size_classes.h], [
   mkdir -p "${objroot}include/jemalloc/internal"
-  "${SHELL}" "${srcdir}/include/jemalloc/internal/size_classes.sh" "${LG_QUANTA}" ${LG_TINY_MIN} "${LG_PAGE_SIZES}" ${LG_SIZE_CLASS_GROUP} > "${objroot}include/jemalloc/internal/size_classes.h"
+  "${SHELL}" "${srcdir}/include/jemalloc/internal/size_classes.sh" "${LG_QUANTA}" ${LG_TINY_MIN} "${LG_PAGE_SIZES}" 2 > "${objroot}include/jemalloc/internal/size_classes.h"
 ], [
   SHELL="${SHELL}"
   srcdir="${srcdir}"
@@ -2030,7 +2024,6 @@ AC_CONFIG_COMMANDS([include/jemalloc/internal/size_classes.h], [
   LG_QUANTA="${LG_QUANTA}"
   LG_TINY_MIN=${LG_TINY_MIN}
   LG_PAGE_SIZES="${LG_PAGE_SIZES}"
-  LG_SIZE_CLASS_GROUP=${LG_SIZE_CLASS_GROUP}
 ])
 AC_CONFIG_COMMANDS([include/jemalloc/jemalloc_protos_jet.h], [
   mkdir -p "${objroot}include/jemalloc"