Fix tests build when --with-install-suffix is set.

Add test/jemalloc_test.h.in, which is processed to include
jemalloc/jemalloc@install_suffix@.h, so that test programs can include
it without worrying about the install suffix.

jemalloc/test/allocm.c

@@ -3,7 +3,7 @@
 #include <stdint.h>
 
 #define	JEMALLOC_MANGLE
-#include "jemalloc/jemalloc.h"
+#include "jemalloc_test.h"
 
 #define CHUNK 0x400000
 /* #define MAXALIGN ((size_t)0x80000000000LLU) */

jemalloc/test/jemalloc_test.h.in

@@ -0,0 +1,6 @@
+/*
+ * This header should be included by tests, rather than directly including
+ * jemalloc/jemalloc.h, because --with-install-suffix may cause the header to
+ * have a different name.
+ */
+#include "jemalloc/jemalloc@install_suffix@.h"

jemalloc/test/posix_memalign.c

@@ -5,7 +5,7 @@
 #include <string.h>
 
 #define	JEMALLOC_MANGLE
-#include "jemalloc/jemalloc.h"
+#include "jemalloc_test.h"
 
 #define CHUNK 0x400000
 /* #define MAXALIGN ((size_t)0x80000000000LLU) */

jemalloc/test/rallocm.c

@@ -3,7 +3,7 @@
 #include <string.h>
 
 #define	JEMALLOC_MANGLE
-#include "jemalloc/jemalloc.h"
+#include "jemalloc_test.h"
 
 int
 main(void)

jemalloc/test/thread_arena.c

@@ -4,7 +4,7 @@
 #include <string.h>
 
 #define	JEMALLOC_MANGLE
-#include "jemalloc/jemalloc.h"
+#include "jemalloc_test.h"
 
 void *
 thread_start(void *arg)