Changes allow to switch between builtin and external lz4 version

builtins/lz4/CMakeLists.txt

@@ -23,17 +23,18 @@ unset(LZ4_FOUND CACHE)
 unset(LZ4_FOUND PARENT_SCOPE)
 set(LZ4_FOUND TRUE CACHE BOOL "" FORCE)
 
-file(STRINGS lz4.h LZ4_H REGEX "^#define LZ4_VERSION_[A-Z]+[ ]+[0-9]+$")
+file(STRINGS "lz4.h" LZ4_H REGEX "^#define LZ4_VERSION_[A-Z]+[ ]+[0-9]+.*$")
 string(REGEX REPLACE ".+LZ4_VERSION_MAJOR[ ]+([0-9]+).*$"   "\\1" LZ4_VERSION_MAJOR "${LZ4_H}")
 string(REGEX REPLACE ".+LZ4_VERSION_MINOR[ ]+([0-9]+).*$"   "\\1" LZ4_VERSION_MINOR "${LZ4_H}")
 string(REGEX REPLACE ".+LZ4_VERSION_RELEASE[ ]+([0-9]+).*$" "\\1" LZ4_VERSION_PATCH "${LZ4_H}")
 set(LZ4_VERSION_STRING "${LZ4_VERSION_MAJOR}.${LZ4_VERSION_MINOR}.${LZ4_VERSION_PATCH}")
+unset(LZ4_H)
 
-set(LZ4_VERSION ${LZ4_VERSION_STRING} CACHE INTERNAL "")
-set(LZ4_VERSION_STRING ${LZ4_VERSION_STRING} CACHE INTERNAL "")
+set(LZ4_VERSION ${LZ4_VERSION_STRING} CACHE INTERNAL "" FORCE)
+set(LZ4_VERSION_STRING ${LZ4_VERSION_STRING} CACHE INTERNAL "" FORCE)
 
-set(LZ4_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE INTERNAL "")
-set(LZ4_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR} CACHE INTERNAL "")
+set(LZ4_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE INTERNAL "" FORCE)
+set(LZ4_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR} CACHE INTERNAL "" FORCE)
 
 add_library(lz4 STATIC ${LZ4_PUBLIC_HEADERS} ${LZ4_PRIVATE_HEADERS} ${LZ4_SOURCES})
 set_target_properties(lz4 PROPERTIES C_VISIBILITY_PRESET hidden POSITION_INDEPENDENT_CODE ON)