With glibc-2.23 and earlier (e.g. RHEL7), crash build fails with errors
like this due to EM_RISCV undeclared:

  $ make -j 24 warn
  TARGET: X86_64
  CRASH: 8.0.2++
  GDB: 10.2
  ...
  symbols.c: In function 'is_kernel':
  symbols.c:3746:8: error: 'EM_RISCV' undeclared (first use in this function)
     case EM_RISCV:
          ^
  ...

Define EM_RISCV as 243 [1][2] if not defined.

[1] https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=94e73c95d9b5
[2] http://www.sco.com/developers/gabi/latest/ch4.eheader.html

Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>
---
 defs.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/defs.h b/defs.h
index d3d837631632..08ac4dc96a92 100644
--- a/defs.h
+++ b/defs.h
@@ -3493,6 +3493,10 @@ struct arm64_stackframe {
 #define _MAX_PHYSMEM_BITS       48
 #endif  /* MIPS64 */

+#ifndef EM_RISCV
+#define EM_RISCV               243
+#endif
+
 #ifdef RISCV64
 #define _64BIT_
 #define MACHINE_TYPE           "RISCV64"
--
1.8.3.1