[llvm-rc] Allow dashes as part of resource name strings

This matches what MS rc.exe allows in practice. I'm not aware of
any legal syntax case that are broken by allowing dashes as part
of what the tokenizer considers an Identifier - but I'm not
very well versed in the RC syntax either, can @amccarth think of
any case that would be broken by this?

This fixes downstream bug
msys2/MINGW-packages#9180.

Additionally, rc.exe allows such resource name strings to be surrounded
by quotes, ending up with e.g.

    Resource name (string): "QUOTEDNAME"

(i.e., the quotes end up as part of the string), which llvm-rc doesn't
support yet either. (I'm not aware of such cases in the wild though,
but resource string names with dashes do exist.)

This also allows including files with unquoted paths, with filenames
containing dashes (which fixes
msys2/MINGW-packages#9130, which has been
worked around differently so far).

Differential Revision: https://reviews.llvm.org/D106598

Author: mstorsjo

llvm/test/tools/llvm-rc/Inputs/resname-string.rc

@@ -0,0 +1,2 @@
+stringname RCDATA { "foo" }
+name-with-dashes/and/slashes RCDATA { "foo" }

llvm/test/tools/llvm-rc/Inputs/tokens.rc

@@ -1,5 +1,6 @@
 1 + 2 - 3214L & 0x120894 032173 2|&~+(-7){0xabcdef 0xABCDEFl} Begin End
 He11o LLVM
+identifier-with-dashes
 
 "RC string test.",L"Another RC string test.'&{",42,100
 

llvm/test/tools/llvm-rc/resname-string.test

@@ -0,0 +1,5 @@
+; RUN: llvm-rc -no-preprocess /FO %t.res -- %p/Inputs/resname-string.rc
+; RUN: llvm-readobj %t.res | FileCheck %s
+
+; CHECK: Resource name (string): STRINGNAME
+; CHECK: Resource name (string): NAME-WITH-DASHES/AND/SLASHES

llvm/test/tools/llvm-rc/tokenizer.test

@@ -27,6 +27,7 @@
 ; CHECK-NEXT:  BlockEnd: End
 ; CHECK-NEXT:  Identifier: He11o
 ; CHECK-NEXT:  Identifier: LLVM
+; CHECK-NEXT:  Identifier: identifier-with-dashes
 ; CHECK-NEXT:  String: "RC string test."
 ; CHECK-NEXT:  Comma: ,
 ; CHECK-NEXT:  String: L"Another RC string test.'&{"

llvm/tools/llvm-rc/ResourceScriptToken.cpp

@@ -288,7 +288,7 @@ bool Tokenizer::canContinueIdentifier() const {
   assert(!streamEof());
   const char CurChar = Data[Pos];
   return std::isalnum(CurChar) || CurChar == '_' || CurChar == '.' ||
-         CurChar == '/' || CurChar == '\\';
+         CurChar == '/' || CurChar == '\\' || CurChar == '-';
 }
 
 bool Tokenizer::canStartInt() const {