[ELF][HEXAGON] Add R_HEX_B13_PCREL relocation support

Differential Revision: https://reviews.llvm.org/D51166

llvm-svn: 340693
diff --git a/lld/test/ELF/hexagon.s b/lld/test/ELF/hexagon.s
index f5874c8..4efd437 100644
--- a/lld/test/ELF/hexagon.s
+++ b/lld/test/ELF/hexagon.s
@@ -202,3 +202,7 @@
 # R_HEX_B9_PCREL_X:
 {r0=#1 ; jump ##_start}
 # CHECK: jump 0x11000
+
+# R_HEX_B13_PCREL
+if (r0 == #0) jump:t #_start
+# CHECK: if (r0==#0) jump:t 0x11000