Add hooking functionality

This allows us to hook chosen functions and do interesting things there (in
particular: reentrancy checking).

test/unit/hooks.c

@@ -0,0 +1,38 @@
+#include "test/jemalloc_test.h"
+
+static bool hook_called = false;
+
+static void
+hook() {
+	hook_called = true;
+}
+
+static int
+func_to_hook(int arg1, int arg2) {
+	return arg1 + arg2;
+}
+
+#define func_to_hook JEMALLOC_HOOK(func_to_hook, hooks_libc_hook)
+
+TEST_BEGIN(unhooked_call) {
+	hooks_libc_hook = NULL;
+	hook_called = false;
+	assert_d_eq(3, func_to_hook(1, 2), "Hooking changed return value.");
+	assert_false(hook_called, "Nulling out hook didn't take.");
+}
+TEST_END
+
+TEST_BEGIN(hooked_call) {
+	hooks_libc_hook = &hook;
+	hook_called = false;
+	assert_d_eq(3, func_to_hook(1, 2), "Hooking changed return value.");
+	assert_true(hook_called, "Hook should have executed.");
+}
+TEST_END
+
+int
+main(void) {
+	return test(
+	    unhooked_call,
+	    hooked_call);
+}

test/unit/prof_accum.c

@@ -76,6 +76,6 @@ TEST_END
 
 int
 main(void) {
-	return test(
+	return test_no_reentrancy(
 	    test_idump);
 }

test/unit/prof_active.c

@@ -112,6 +112,6 @@ TEST_END
 
 int
 main(void) {
-	return test(
+	return test_no_reentrancy(
 	    test_prof_active);
 }

test/unit/prof_gdump.c

@@ -69,6 +69,6 @@ TEST_END
 
 int
 main(void) {
-	return test(
+	return test_no_reentrancy(
 	    test_gdump);
 }

test/unit/prof_reset.c

@@ -278,7 +278,7 @@ main(void) {
 	/* Intercept dumping prior to running any tests. */
 	prof_dump_open = prof_dump_open_intercept;
 
-	return test(
+	return test_no_reentrancy(
 	    test_prof_reset_basic,
 	    test_prof_reset_cleanup,
 	    test_prof_reset,

test/unit/prof_tctx.c

@@ -41,6 +41,6 @@ TEST_END
 
 int
 main(void) {
-	return test(
+	return test_no_reentrancy(
 	    test_prof_realloc);
 }

test/unit/tsd.c

@@ -79,6 +79,7 @@ thd_start(void *arg) {
 }
 
 TEST_BEGIN(test_tsd_main_thread) {
+	test_skip_if(test_is_reentrant());
 	thd_start((void *)(uintptr_t)0xa5f3e329);
 }
 TEST_END