8336406: Add support for FP16 binary operations

[Bhavana-Kilambi]

This patch adds middle end support in C2 for a few FP16 binary operations, namely - subtract, multiply, divide, min and max. It also adds aarch64 backend support for these operations.

Tested JTREG tests - hotspot/jtreg/compiler/vectorization/TestFloat16VectorOps.java, hotspot/jtreg/compiler/vectorization/TestFloat16VectorReinterpretConv.java, hotspot/jtreg/compiler/intrinsics/float16 and test/jdk/java/lang/Float16 and they successfully pass on aarch64 and x86 machines.

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Progress

• [x] Change must not contain extraneous whitespace

Issue

• JDK-8336406: Add support for FP16 binary operations (Enhancement - P4)

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