Fix warnings about comparison/assignement between signed and unsigned types. Submitted by timeless.

src/compiler/preprocessor/atom.c

@@ -619,7 +619,7 @@ static int AddAtomFixed(AtomTable *atable, const char *s, int atom)
 
 int InitAtomTable(AtomTable *atable, int htsize)
 {
-    int ii;
+    unsigned int ii;
 
     htsize = htsize <= 0 ? INIT_HASH_TABLE_SIZE : htsize;
     if (!InitStringTable(&atable->stable))

src/compiler/preprocessor/symbols.c

@@ -152,7 +152,7 @@ Symbol *NewSymbol(SourceLoc *loc, Scope *fScope, int name, symbolkind kind)
 {
     Symbol *lSymb;
     char *pch;
-    int ii;
+    unsigned int ii;
 
     lSymb = (Symbol *) mem_Alloc(fScope->pool, sizeof(Symbol));
     lSymb->left = NULL;

src/compiler/preprocessor/tokens.c

@@ -205,7 +205,7 @@ void DeleteTokenStream(TokenStream *pTok)
 void RecordToken(TokenStream *pTok, int token, yystypepp * yylvalpp)
 {
     const char *s;
-    unsigned char *str=NULL;
+    char *str=NULL;
 
     if (token > 256)
         lAddByte(pTok, (unsigned char)((token & 0x7f) + 0x80));