Fix building packages with LTO when CONFIG_PKG_ASLR_PIE is enabled.
Despite comment of PR lto/80838, it seems that GCC needs -fPIC on linker
command line, even if all objects are -fPIC. This may change as PR
lto/80838 is merged into 8.1
compile-tested: ar71xx, ath79
Fix commits:
6dac92a42e8c11133c9d07940acc34e7397eef69ef16a394d2ef96d1e34a47b42137ce73fc67b614154c0c4006804c51e1e6
Signed-off-by: Julien Dusser <julien.dusser@free.fr>