HTTP parser: fixed parsing of target after literal space character.

In theory, all space characters in request target must be encoded; however,
some clients may violate the specification.  For the sake of interoperability,
Unit supports unencoded space characters.

Previously, if there was a space character before the extension or arguments
parts, those parts weren't recognized.  Also, quoted symbols and complex
target weren't detected after a space character.

test/test_python_application.py

@@ -71,6 +71,37 @@ class TestPythonApplication(TestApplicationPython):
             'Query-String header',
         )
 
+    def test_python_application_query_string_space(self):
+        self.load('query_string')
+
+        resp = self.get(url='/ ?var1=val1&var2=val2')
+        self.assertEqual(
+            resp['headers']['Query-String'],
+            'var1=val1&var2=val2',
+            'Query-String space',
+        )
+
+        resp = self.get(url='/ %20?var1=val1&var2=val2')
+        self.assertEqual(
+            resp['headers']['Query-String'],
+            'var1=val1&var2=val2',
+            'Query-String space 2',
+        )
+
+        resp = self.get(url='/ %20 ?var1=val1&var2=val2')
+        self.assertEqual(
+            resp['headers']['Query-String'],
+            'var1=val1&var2=val2',
+            'Query-String space 3',
+        )
+
+        resp = self.get(url='/blah %20 blah? var1= val1 & var2=val2')
+        self.assertEqual(
+            resp['headers']['Query-String'],
+            ' var1= val1 & var2=val2',
+            'Query-String space 4',
+        )
+
     def test_python_application_query_string_empty(self):
         self.load('query_string')