fix some gcc 4 warnings in xpcom. patch by Christian Haberstroh. b=382753 r=bent sr=bsmedberg

xpcom/components/nsComponentManager.cpp

@@ -2746,7 +2746,7 @@ nsComponentManagerImpl::GetLoaderType(const char *typeStr)
 
     const nsDependentCString type(typeStr);
 
-    for (int i=0; i < mLoaderData.Length(); ++i) {
+    for (unsigned int i = 0; i < mLoaderData.Length(); ++i) {
         if (mLoaderData[i].type == type)
             return i;
     }
@@ -3100,7 +3100,7 @@ nsComponentManagerImpl::LoadDeferredModules(nsTArray<DeferredModule> &aDeferred)
     // 1) they're all gone
     // 2) we loop through and none of them succeed
 
-    PRInt32 lastCount = PR_INT32_MAX;
+    PRUint32 lastCount = PR_UINT32_MAX;
     while (aDeferred.Length() > 0 &&
            lastCount > aDeferred.Length()) {
 

xpcom/io/nsLocalFileOSX.cpp

@@ -2262,7 +2262,7 @@ nsresult nsLocalFile::CFStringReftoUTF8(CFStringRef aInStrRef, nsACString& aOutS
                               kCFStringEncodingUTF8, 0, PR_FALSE, nsnull, 0, &usedBufLen);
   if (charsConverted == inStrLen) {
     aOutStr.SetLength(usedBufLen);
-    if (aOutStr.Length() != usedBufLen)
+    if (aOutStr.Length() != (unsigned int)usedBufLen)
       return NS_ERROR_OUT_OF_MEMORY;
     UInt8 *buffer = (UInt8*) aOutStr.BeginWriting();