cmake: Report more compiler details in summary

CMakeLists.txt

@@ -343,7 +343,7 @@ message("Valgrind .............................. ${SECP256K1_VALGRIND}")
 get_directory_property(definitions COMPILE_DEFINITIONS)
 string(REPLACE ";" " " definitions "${definitions}")
 message("Preprocessor defined macros ........... ${definitions}")
-message("C compiler ............................ ${CMAKE_C_COMPILER}")
+message("C compiler ............................ ${CMAKE_C_COMPILER_ID} ${CMAKE_C_COMPILER_VERSION}, ${CMAKE_C_COMPILER}")
 message("CFLAGS ................................ ${CMAKE_C_FLAGS}")
 get_directory_property(compile_options COMPILE_OPTIONS)
 string(REPLACE ";" " " compile_options "${compile_options}")