[ELF] Remove default argument for lambda.

This is not really OK in C++11, and GCc triggers a warning.
We can switch back to default arguments when C++14 will be the
minimum version of the standard supported, see:
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#974

Ack'ed by Rafael.

llvm-svn: 313550
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index a7c9191..4f5a450 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -835,17 +835,17 @@
   if (Script->Opt.HasSections)
     return;
 
-  auto Add = [](StringRef S, int64_t Pos = -1) {
+  auto Add = [](StringRef S, int64_t Pos) {
     return addOptionalRegular<ELFT>(S, Out::ElfHeader, Pos, STV_DEFAULT);
   };
 
   ElfSym::Bss = Add("__bss_start", 0);
-  ElfSym::End1 = Add("end");
-  ElfSym::End2 = Add("_end");
-  ElfSym::Etext1 = Add("etext");
-  ElfSym::Etext2 = Add("_etext");
-  ElfSym::Edata1 = Add("edata");
-  ElfSym::Edata2 = Add("_edata");
+  ElfSym::End1 = Add("end", -1);
+  ElfSym::End2 = Add("_end", -1);
+  ElfSym::Etext1 = Add("etext", -1);
+  ElfSym::Etext2 = Add("_etext", -1);
+  ElfSym::Edata1 = Add("edata", -1);
+  ElfSym::Edata2 = Add("_edata", -1);
 }
 
 // Sort input sections by section name suffixes for