Drop umbrella include from 5 small .c files (batch 1)

Replaces #include "jemalloc_internal_includes.h" with explicit
per-symbol includes in five small TUs:

  src/edata.c       -> edata.h
  src/exp_grow.c    -> exp_grow.h
  src/ticker.c      -> ticker.h
  src/bin_info.c    -> assert.h, bin_info.h
  src/counter.c     -> counter.h, witness.h

One latent hermeticity bug surfaced: sz.h's
sz_large_size_classes_disabled() inline references
opt_disable_large_size_classes (declared in
jemalloc_internal_externs.h) but sz.h didn't include that header.
Worked under the umbrella but breaks once consumers stop including
everything.  Added the include to sz.h so it stands on its own.

Step 6 (Option B) of the cyclical-dep cleanup, batch 1 of N.

include/jemalloc/internal/sz.h

@@ -3,6 +3,7 @@
 
 #include "jemalloc/internal/jemalloc_preamble.h"
 #include "jemalloc/internal/bit_util.h"
+#include "jemalloc/internal/jemalloc_internal_externs.h"
 #include "jemalloc/internal/pages.h"
 #include "jemalloc/internal/sc.h"
 #include "jemalloc/internal/util.h"

src/bin_info.c

@@ -1,6 +1,6 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
-#include "jemalloc/internal/jemalloc_internal_includes.h"
 
+#include "jemalloc/internal/assert.h"
 #include "jemalloc/internal/bin_info.h"
 
 bin_info_t bin_infos[SC_NBINS];

src/counter.c

@@ -1,7 +1,7 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
-#include "jemalloc/internal/jemalloc_internal_includes.h"
 
 #include "jemalloc/internal/counter.h"
+#include "jemalloc/internal/witness.h"
 
 bool
 counter_accum_init(counter_accum_t *counter, uint64_t interval) {

src/edata.c

@@ -1,5 +1,6 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
-#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/edata.h"
 
 ph_gen(, edata_avail, edata_t, avail_link, edata_esnead_comp)
     ph_gen(, edata_heap, edata_t, heap_link, edata_snad_comp)

src/exp_grow.c

@@ -1,5 +1,6 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
-#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/exp_grow.h"
 
 void
 exp_grow_init(exp_grow_t *exp_grow) {

src/ticker.c

@@ -1,5 +1,6 @@
 #include "jemalloc/internal/jemalloc_preamble.h"
-#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/ticker.h"
 
 /*
  * To avoid using floating point math down core paths (still necessary because