Add COREV branching immediate instructions, and GCC tests.

Created by: EnricoTabanelli

Files changed:

*gcc/common/config/riscv/riscv-common.cc: Add "xcorev" and "xcorevbi" in riscv_implied_info_t and riscv_ext_flag_tablev.
*gcc/config/riscv/corev.md: Add COREV machine description.
*gcc/config/riscv/predicates.md: Add branch_simm5_operand predicate.
*gcc/config/riscv/riscv.cc: Modify riscv_emit_int_compare() function to support COREV branching immediate.
*gcc/config/riscv/riscv.md: Include COREV machine description.
*gcc/config/riscv/riscv.opt: Add COREV_BI target mask.
*gcc/testsuite/gcc.target/riscv/cv-bi-beqimm-compile.c: Add COREV branching immediate tests for GCC testsuite.
*gcc/testsuite/gcc.target/riscv/cv-bi-beqimm.c: Likewise.
*gcc/testsuite/gcc.target/riscv/cv-bi-bneimm-compile.c: Likewise.
*gcc/testsuite/gcc.target/riscv/cv-bi-bneimm.c: Likewise.

Signed-off-by: Enrico Tabanelli enrico.tabanelli@embecosm.com