[mips][ias] Support .dtprel[d]word and .tprel[d]word directives

Assembler directives .dtprelword, .dtpreldword, .tprelword, and
.tpreldword generates relocations R_MIPS_TLS_DTPREL32, R_MIPS_TLS_DTPREL64,
R_MIPS_TLS_TPREL32, and R_MIPS_TLS_TPREL64 respectively.

The main motivation for this patch is to be able to write test cases
for checking correctness of the LLD linker's behaviour.

Differential Revision: https://reviews.llvm.org/D23669

llvm-svn: 279439
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 6c8828f..cfe25f9 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -127,6 +127,22 @@
     EmitCOFFSecRel32(Sym);
 }
 
+void MCStreamer::EmitDTPRel64Value(const MCExpr *Value) {
+  report_fatal_error("unsupported directive in streamer");
+}
+
+void MCStreamer::EmitDTPRel32Value(const MCExpr *Value) {
+  report_fatal_error("unsupported directive in streamer");
+}
+
+void MCStreamer::EmitTPRel64Value(const MCExpr *Value) {
+  report_fatal_error("unsupported directive in streamer");
+}
+
+void MCStreamer::EmitTPRel32Value(const MCExpr *Value) {
+  report_fatal_error("unsupported directive in streamer");
+}
+
 void MCStreamer::EmitGPRel64Value(const MCExpr *Value) {
   report_fatal_error("unsupported directive in streamer");
 }