testsuite: Use printk for all test output where possible.

- Remove the printf support leaving the direct printk support configured
  with TESTS_USE_PRINTK and all other output goes via a buffered vsniprintf
  call to printk.
- Control the test's single init for functions and global data with
  TEST_INIT and not CONFIGURE_INIT. They are now separate.

Updates #3170.

testsuites/benchmarks/dhrystone/init.c

@@ -16,6 +16,8 @@
 #include "config.h"
 #endif
 
+#define TEST_INIT
+
 #include "tmacros.h"
 
 const char rtems_test_name[] = "DHRYSTONE";

testsuites/benchmarks/linpack/init.c

@@ -16,6 +16,8 @@
 #include "config.h"
 #endif
 
+#define TEST_INIT
+
 #include "tmacros.h"
 
 const char rtems_test_name[] = "LINPACK";

testsuites/benchmarks/whetstone/init.c

@@ -16,6 +16,8 @@
 #include "config.h"
 #endif
 
+#define TEST_INIT
+
 #include "tmacros.h"
 
 const char rtems_test_name[] = "WHETSTONE";