Git: Prepend -e to the pattern on grep

This fixes searching for patterns that start with dash.

Change-Id: I824f64151842008a034757de6a00fd8a6cc46d72
Reviewed-by: André Hartmann <aha_1980@gmx.de>

src/plugins/git/gitgrep.cpp

@@ -154,7 +154,7 @@ public:
             arguments << "-P";
         else
             arguments << "-F";
-        arguments << m_parameters.text;
+        arguments << "-e" << m_parameters.text;
         GitGrepParameters params = m_parameters.extensionParameters.value<GitGrepParameters>();
         if (!params.ref.isEmpty()) {
             arguments << params.ref;