Implement missing Math logarithm functions from ES6 (#3617)

Math.log2, Math.log10, Math.log1p, Math.expm1

C implementation ported from fdlibm

Part of Issue #3568

JerryScript-DCO-1.0-Signed-off-by: Rafal Walczyna r.walczyna@samsung.com

tests/jerry/es2015/math-log2.js

@@ -0,0 +1,27 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var p_zero = 0.0;
+var n_zero = -p_zero;
+
+assert(isNaN(Math.log2(NaN)));
+assert(isNaN(Math.log2(-42)));
+assert(isNaN(Math.log2(-3.0)));
+assert(Math.log2(n_zero) === Number.NEGATIVE_INFINITY);
+assert(Math.log2(p_zero) === Number.NEGATIVE_INFINITY);
+assert(Math.log2(1) === p_zero);
+assert(Math.log2(Number.POSITIVE_INFINITY) === Number.POSITIVE_INFINITY);
+assert(Math.log2(2.0) === 1);
+assert(Math.log2(4.0) === 2)
+assert(Math.log2(1024.0) === 10)