Ensure that the test version of the command line tool is stable for benchmarking (#2076)

Some benchmark suites contain test cases that have nonreproducible
behaviour. This is mostly caused by relying on "now" when dealing
with dates or timestamps, instead of using a fixed moment. (A
notorious example is the crypto-aes.js test case of the sunspider
bechmark suite, where the heap memory consumption can vary between
34K-41K heap because of using `(new Date()).getTime()`.)

This commit renames the jerry-minimal command line tool to
jerry-test (to better reflect its purpose) and adds extra code,
which intercepts some calls to libc (`gettimeofday`, `rand`) and
pins their results to some fixed values. This makes the tool
useless in a general case but ensures stable results when
benchmarking -- for which it is mostly used.

As a side effect, the commit also changes jerry-libc by making all
libc functions weak symbols to allow their override from
application code.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

tools/run-tests.py

@@ -122,8 +122,8 @@ JERRY_BUILDOPTIONS = [
             ['--jerry-libc=off', '--compile-flag=-m32', '--cpointer-32bit=on', '--system-allocator=on']),
     Options('buildoption_test-external_context',
             ['--jerry-libc=off', '--external-context=on']),
-    Options('buildoption_test-cmdline_minimal',
-            ['--jerry-cmdline-minimal=on']),
+    Options('buildoption_test-cmdline_test',
+            ['--jerry-cmdline-test=on']),
     Options('buildoption_test-cmdline_snapshot',
             ['--jerry-cmdline-snapshot=on']),
 ]