remove automatic splitting from $$() expansions

$$(FOO) would automatically split the contents of the environment
variable at whitespace (and interpret quoting inside it). the way to
prevent the splitting (but not the quote interpretation) would be using
"$$(FOO)".

this behavior is entirely unexpected and thus an incredibly effective
source of quoting problems - according to a grep over the whole qt
sources, there isn't a single case where things were done right. in qt
creator, well over half the cases are wrong.

also, the "feature" seems entirely pointless: nobody uses spaces as
separators in environment variables.

consequently, simply remove it, even in a patch release. i'm postulating
that nobody will complain.

Change-Id: I9ed3df1b0d1ef602acd78ceb118611d294561da6
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

dist/changes-5.0.2

@@ -107,6 +107,12 @@ Qt for Windows CE
 *                          Tools                                           *
 ****************************************************************************
 
+qmake
+-----
+
+ - $$(VAR) style environment variable expansions will not split on
+   whitespace any more. Use $$split() if necessary.
+
 
 ****************************************************************************
 *                          Plugins                                         *

qmake/library/qmakeevaluator.cpp

@@ -453,9 +453,9 @@ void QMakeEvaluator::evaluateExpression(
             break; }
         case TokEnvVar: {
             const ProString &var = getStr(tokPtr);
-            const ProStringList &val = split_value_list(m_option->getEnv(var.toQString(m_tmp1)));
-            debugMsg(2, "env var %s => %s", dbgStr(var), dbgStrList(val));
-            addStrList(val, tok, ret, pending, joined);
+            const ProString &val = ProString(m_option->getEnv(var.toQString(m_tmp1)));
+            debugMsg(2, "env var %s => %s", dbgStr(var), dbgStr(val));
+            addStr(val, ret, pending, joined);
             break; }
         case TokFuncName: {
             const ProKey &func = getHashStr(tokPtr);