cmake: remove spaces between `IF` and `(` for policies

Our CMake coding style dictates that there should be no space between
`IF` and its opening `(`. Adjust our policy statements to honor this
style.

CMakeLists.txt

@@ -14,10 +14,10 @@
 PROJECT(libgit2 C)
 CMAKE_MINIMUM_REQUIRED(VERSION 2.8.11)
 CMAKE_POLICY(SET CMP0015 NEW)
-IF (POLICY CMP0051)
+IF(POLICY CMP0051)
 	CMAKE_POLICY(SET CMP0051 NEW)
 ENDIF()
-IF (POLICY CMP0042)
+IF(POLICY CMP0042)
 	CMAKE_POLICY(SET CMP0042 NEW)
 ENDIF()