Add ability to skip installing license with INSTALL_LICENSE option (#981)

This is useful for Debian, where the package already includes copyright
information and therefore installing the license into
/usr/share/licenses is not needed.

Upstream support for an option to disable installing the license is much
better than patching it on the packaging side (which needs to be
continuously updated).

CMakeLists.txt

@@ -76,6 +76,7 @@ option(ENABLE_PROPRIETARY_GPU_DRIVER_API "Enable proprietary GPU driver API (NVM
 option(BUILD_TESTS "Build tests" OFF) # Also create test executables
 option(SET_TWEAK "Add tweak to project version" ON) # This is set to off by github actions for release builds
 option(IS_MUSL "Build with musl libc" OFF) # Used by Github Actions
+option(INSTALL_LICENSE "Install license into /usr/share/licenses" ON)
 
 set(BINARY_LINK_TYPE_OPTIONS dlopen dynamic static)
 set(BINARY_LINK_TYPE dlopen CACHE STRING "How to link fastfetch")
@@ -1173,10 +1174,12 @@ install(
     DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/${CMAKE_PROJECT_NAME}"
 )
 
-install(
-    FILES "${CMAKE_SOURCE_DIR}/LICENSE"
-    DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/licenses/${CMAKE_PROJECT_NAME}"
-)
+if(INSTALL_LICENSE)
+    install(
+        FILES "${CMAKE_SOURCE_DIR}/LICENSE"
+        DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/licenses/${CMAKE_PROJECT_NAME}"
+    )
+endif()
 
 install(
     FILES "${PROJECT_BINARY_DIR}/fastfetch.1"