Subzero: Misc fixes/cleanup.

1. Fix MINIMAL build.
  (a) Add a void cast to a var only used in asserts.
  (b) Use "REQUIRES:" instead of "REQUIRES" in a .ll file.
2. Use StrError instead of StrDump for errors.
3. Use a lambda instead of a functor because C++11.
4. Explicit check for -filetype=obj in a non-dump-enabled build, to avoid cryptic downstream error messages.
5. Run "make format" which was neglected earlier.

BUG= none
R=kschimpf@google.com

Review URL: https://codereview.chromium.org/1284493003.
diff --git a/src/IceInstARM32.cpp b/src/IceInstARM32.cpp
index 15664f7..add4df0 100644
--- a/src/IceInstARM32.cpp
+++ b/src/IceInstARM32.cpp
@@ -479,7 +479,7 @@
   Ostream &Str = Func->getContext()->getStrEmit();
   assert(getSrcSize() == 1);
   assert(getDest()->hasReg());
-  Str << "\t"<< Opcode << getPredicate() << "\t";
+  Str << "\t" << Opcode << getPredicate() << "\t";
   getDest()->emit(Func);
   Str << ", ";
   getSrc(0)->emit(Func);
@@ -649,7 +649,7 @@
   assert(getSrcSize() == 1);
   assert(getDest()->hasReg());
   Type Ty = getSrc(0)->getType();
-  Str << "\t"<< Opcode << getWidthString(Ty) << getPredicate() << "\t";
+  Str << "\t" << Opcode << getWidthString(Ty) << getPredicate() << "\t";
   getDest()->emit(Func);
   Str << ", ";
   getSrc(0)->emit(Func);