Add heap profiling tests.

Fix a regression in prof_dump_ctx() due to an uninitized variable.  This
was caused by revision 4f37ef693e, so no
releases are affected.

test/unit/prof_gdump.c

@@ -0,0 +1,56 @@
+#include "test/jemalloc_test.h"
+
+#ifdef JEMALLOC_PROF
+const char *malloc_conf = "prof:true,prof_active:false,prof_gdump:true";
+#endif
+
+static bool did_prof_dump_open;
+
+static int
+prof_dump_open_intercept(bool propagate_err, const char *filename)
+{
+	int fd;
+
+	did_prof_dump_open = true;
+
+	fd = open("/dev/null", O_WRONLY);
+	assert_d_ne(fd, -1, "Unexpected open() failure");
+
+	return (fd);
+}
+
+TEST_BEGIN(test_gdump)
+{
+	bool active;
+	void *p, *q;
+
+	test_skip_if(!config_prof);
+
+	active = true;
+	assert_d_eq(mallctl("prof.active", NULL, NULL, &active, sizeof(active)),
+	    0, "Unexpected mallctl failure while activating profiling");
+
+	prof_dump_open = prof_dump_open_intercept;
+
+	did_prof_dump_open = false;
+	p = mallocx(chunksize, 0);
+	assert_ptr_not_null(p, "Unexpected mallocx() failure");
+	assert_true(did_prof_dump_open, "Expected a profile dump");
+
+	did_prof_dump_open = false;
+	q = mallocx(chunksize, 0);
+	assert_ptr_not_null(q, "Unexpected mallocx() failure");
+	assert_true(did_prof_dump_open, "Expected a profile dump");
+
+	dallocx(p, 0);
+	dallocx(q, 0);
+}
+TEST_END
+
+int
+main(void)
+{
+
+	return (test(
+	    test_gdump));
+}