[llvm-rc] Add ICON and HTML parsing ability (parser, pt 2/8).

This extends the current llvm-rc parser by ICON and HTML resources.
Moreover, some tests have been slightly rewritten.

Thanks for Nico Weber for his original work in this area.

Differential Revision: https://reviews.llvm.org/D36891

llvm-svn: 311939
diff --git a/llvm/test/tools/llvm-rc/Inputs/parser-html-bad-string.rc b/llvm/test/tools/llvm-rc/Inputs/parser-html-bad-string.rc
new file mode 100644
index 0000000..5edab85
--- /dev/null
+++ b/llvm/test/tools/llvm-rc/Inputs/parser-html-bad-string.rc
@@ -0,0 +1 @@
+200 HTML ThisPassesInTheOriginalToolButDocSaysItShouldBeQuoted