Bump cmake min to 3.20 and add explicit extensions for CMP0115
https://bugs.gentoo.org/953935
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.4)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.20)
 
 project(libcuefile C)
 
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,7 +1,7 @@
 add_definitions(-DYY_NEVER_INTERACTIVE)
 include_directories(${libcuefile_SOURCE_DIR}/include)
 
-add_library(cuefile-shared SHARED cd cdtext cue_parse cue_print cue_scan cuefile time toc toc_parse toc_print toc_scan)
+add_library(cuefile-shared SHARED cd.c cdtext.c cue_parse.c cue_print.c cue_scan.c cuefile.c time.c toc.h toc_parse.c toc_print.c toc_scan.c)
 set_target_properties(cuefile-shared PROPERTIES OUTPUT_NAME cuefile CLEAN_DIRECT_OUTPUT 1 VERSION 0.0.0 SOVERSION 0)
 
 install(TARGETS cuefile-shared LIBRARY DESTINATION "lib${LIB_SUFFIX}" ARCHIVE DESTINATION "lib${LIB_SUFFIX}")