libnfs: Drop -Wno-implicit-function-declaration

clang builds work without this Workaround

Signed-off-by: Khem Raj <raj.khem@gmail.com>
(cherry picked from commit 61663d2990)
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-oe/recipes-connectivity/libnfs/libnfs_5.0.2.bb

@@ -15,6 +15,3 @@ inherit cmake
 do_install:append() {
 	rm -f ${D}${libdir}/cmake/libnfs/libnfs-config.cmake
 }
-
-# Workaround for clang
-CFLAGS += "-Wno-implicit-function-declaration"