[RISCV] Define RISC-V specific e_flags

Add RISC-V e_flags as defined in the ABI document:

https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md#file-header

Differential Revision: https://reviews.llvm.org/D38310
Patch by Chih-Mao Chen.

llvm-svn: 314386

include/llvm/BinaryFormat/ELF.h

@@ -612,6 +612,17 @@ enum {
 #include "ELFRelocs/Lanai.def"
 };
 
+// RISCV Specific e_flags
+enum : unsigned {
+  EF_RISCV_RVC = 0x0001,
+  EF_RISCV_FLOAT_ABI = 0x0006,
+  EF_RISCV_FLOAT_ABI_SOFT = 0x0000,
+  EF_RISCV_FLOAT_ABI_SINGLE = 0x0002,
+  EF_RISCV_FLOAT_ABI_DOUBLE = 0x0004,
+  EF_RISCV_FLOAT_ABI_QUAD = 0x0006,
+  EF_RISCV_RVE = 0x0008
+};
+
 // ELF Relocation types for RISC-V
 enum {
 #include "ELFRelocs/RISCV.def"