SilverSearcher: Fix finding the tool

The documentation tells the user to adapt the PATH in the Preferences >
Environment > System. Setting that as the environment got lost in
9a0285ba0e

Fixes: QTCREATORBUG-32335
Change-Id: I3e06fe6a5195b5571e723c0e58cb81c592bf1082
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/silversearcher/findinfilessilversearcher.cpp

@@ -9,8 +9,9 @@
 #include <texteditor/findinfiles.h>
 
 #include <utils/async.h>
-#include <utils/qtcprocess.h>
+#include <utils/environment.h>
 #include <utils/qtcassert.h>
+#include <utils/qtcprocess.h>
 #include <utils/qtcsettings.h>
 
 #include <QHBoxLayout>
@@ -50,6 +51,7 @@ static bool isSilverSearcherAvailable()
 {
     Process silverSearcherProcess;
     silverSearcherProcess.setCommand({"ag", {"--version"}});
+    silverSearcherProcess.setEnvironment(Environment::systemEnvironment());
     silverSearcherProcess.start();
     using namespace std::chrono_literals;
     return silverSearcherProcess.waitForFinished(1s)
@@ -88,6 +90,7 @@ static void runSilverSeacher(QPromise<SearchResultItems> &promise,
 
         arguments << "--" << parameters.text << parameters.searchDir.normalizedPathName().toString();
         process.setCommand({"ag", arguments});
+        process.setEnvironment(Environment::systemEnvironment());
     };
 
     FilePath lastFilePath;