Refactor to support more varied testing.

Refactor the test harness to support three types of tests:
- unit: White box unit tests.  These tests have full access to all
  internal jemalloc library symbols.  Though in actuality all symbols
  are prefixed by jet_, macro-based name mangling abstracts this away
  from test code.
- integration: Black box integration tests.  These tests link with
  the installable shared jemalloc library, and with the exception of
  some utility code and configure-generated macro definitions, they have
  no access to jemalloc internals.
- stress: Black box stress tests.  These tests link with the installable
  shared jemalloc library, as well as with an internal allocator with
  symbols prefixed by jet_ (same as for unit tests) that can be used to
  allocate data structures that are internal to the test code.

Move existing tests into test/{unit,integration}/ as appropriate.

Split out internal parts of jemalloc_defs.h.in and put them in
jemalloc_internal_defs.h.in.  This reduces internals exposure to
applications that #include <jemalloc/jemalloc.h>.

Refactor jemalloc.h header generation so that a single header file
results, and the prototypes can be used to generate jet_ prototypes for
tests.  Split jemalloc.h.in into multiple parts (jemalloc_defs.h.in,
jemalloc_macros.h.in, jemalloc_protos.h.in, jemalloc_mangle.h.in) and
use a shell script to generate a unified jemalloc.h at configure time.

Change the default private namespace prefix from "" to "je_".

Add missing private namespace mangling.

Remove hard-coded private_namespace.h.  Instead generate it and
private_unnamespace.h from private_symbols.txt.  Use similar logic for
public symbols, which aids in name mangling for jet_ symbols.

Add test_warn() and test_fail().  Replace existing exit(1) calls with
test_fail() calls.

test/integration/mremap.c

@@ -0,0 +1,59 @@
+#include "test/jemalloc_test.h"
+
+int
+main(void)
+{
+	int ret, err;
+	size_t sz, lg_chunk, chunksize, i;
+	char *p, *q;
+
+	malloc_printf("Test begin\n");
+
+	sz = sizeof(lg_chunk);
+	if ((err = mallctl("opt.lg_chunk", &lg_chunk, &sz, NULL, 0))) {
+		assert(err != ENOENT);
+		malloc_printf("%s(): Error in mallctl(): %s\n", __func__,
+		    strerror(err));
+		ret = 1;
+		goto label_return;
+	}
+	chunksize = ((size_t)1U) << lg_chunk;
+
+	p = (char *)malloc(chunksize);
+	if (p == NULL) {
+		malloc_printf("malloc(%zu) --> %p\n", chunksize, p);
+		ret = 1;
+		goto label_return;
+	}
+	memset(p, 'a', chunksize);
+
+	q = (char *)realloc(p, chunksize * 2);
+	if (q == NULL) {
+		malloc_printf("realloc(%p, %zu) --> %p\n", p, chunksize * 2,
+		    q);
+		ret = 1;
+		goto label_return;
+	}
+	for (i = 0; i < chunksize; i++) {
+		assert(q[i] == 'a');
+	}
+
+	p = q;
+
+	q = (char *)realloc(p, chunksize);
+	if (q == NULL) {
+		malloc_printf("realloc(%p, %zu) --> %p\n", p, chunksize, q);
+		ret = 1;
+		goto label_return;
+	}
+	for (i = 0; i < chunksize; i++) {
+		assert(q[i] == 'a');
+	}
+
+	free(q);
+
+	ret = 0;
+label_return:
+	malloc_printf("Test end\n");
+	return (ret);
+}