Don't set PREFIX variable in cmake

As I can see this variable is not used by rspamd build system. Remove it
because setting it causes a lot of warning with
-DENABLE_CLANG_PLUGIN=ON - PREFIX variable is not documented but used by
cmake internally.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0aa91aa579644e01294d5e3c8d58a90b4a0ff8bc..925408f8c09fe594fce9db65098320e67d1baa4b 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -506,10 +506,6 @@ INCLUDE_DIRECTORIES("${CMAKE_SOURCE_DIR}/"
                "${CMAKE_BINARY_DIR}/src" #Stored in the binary dir
                "${CMAKE_BINARY_DIR}/src/libcryptobox")
 
-IF(CMAKE_INSTALL_PREFIX)
-       SET(PREFIX ${CMAKE_INSTALL_PREFIX})
-ENDIF(CMAKE_INSTALL_PREFIX)
-
 LIST(APPEND CMAKE_REQUIRED_LIBRARIES m)
 
 SET(POE_LOOP "Loop::IO_Poll")