Revert "build: add way to keep unused symbols when linking NetworkManager"

This approach does not seem to work with clang 3.4 (rhel-7). Instead,
make sure we actually use the symbol in NetworkManager so that it gets
preserved for the OVS device plugin.

This reverts commit 684f2acffe.

Makefile.am

@@ -2662,14 +2662,6 @@ $(src_core_libNetworkManagerTest_la_OBJECTS): $(src_libnm_core_public_mkenums_h)
 
 ###############################################################################
 
-# NetworkManager binary also must contain symbols that are not used by the binary
-# itself, but by the plugins (that are dlopened). We need to explicitly include
-# them during linking.
-networkmanager_undefined_symbols = \
-	nm_sudo_call_get_fd \
-	nm_sudo_utils_open_fd \
-	$(NULL)
-
 noinst_PROGRAMS += src/core/NetworkManager-all-sym
 
 src_core_NetworkManager_all_sym_CPPFLAGS = $(src_core_cppflags)
@@ -2684,7 +2676,6 @@ src_core_NetworkManager_all_sym_LDADD = \
 
 src_core_NetworkManager_all_sym_LDFLAGS = \
 	-rdynamic \
-	$(networkmanager_undefined_symbols:%=-u %) \
 	$(SANITIZER_EXEC_LDFLAGS) \
 	$(NULL)
 
@@ -2711,7 +2702,6 @@ src_core_NetworkManager_LDADD = \
 src_core_NetworkManager_LDFLAGS = \
 	-rdynamic \
 	-Wl,--version-script="src/core/NetworkManager.ver" \
-	$(networkmanager_undefined_symbols:%=-u %) \
 	$(SANITIZER_EXEC_LDFLAGS) \
 	$(NULL)
 

src/core/meson.build

@@ -271,17 +271,6 @@ endif
 subdir('devices')
 subdir('settings/plugins')
 
-# NetworkManager binary also must contain symbols that are not used by the binary
-# itself, but by the plugins (that are dlopened). We need to explicitly include
-# them during linking.
-networkmanager_undefined_symbols_args = []
-foreach s: [
-              'nm_sudo_call_get_fd',
-              'nm_sudo_utils_open_fd',
-           ]
-  networkmanager_undefined_symbols_args += ['-u', s]
-endforeach
-
 # NetworkManager binary
 
 # libNetworkManager.a, as built by meson doesn't contain all symbols
@@ -296,9 +285,7 @@ NetworkManager_all_sym = executable(
     nm_deps,
     libudev_dep,
   ],
-  link_args: [
-    '-Wl,--no-gc-sections',
-  ] + networkmanager_undefined_symbols_args,
+  link_args: '-Wl,--no-gc-sections',
   link_whole: [
     libNetworkManager,
     libNetworkManagerBase,
@@ -359,7 +346,7 @@ NetworkManager = executable(
   link_args: [
     '-rdynamic',
     '-Wl,--version-script,@0@'.format(ver_script.full_path()),
-  ] + networkmanager_undefined_symbols_args,
+  ],
   link_depends: ver_script,
   install: true,
   install_dir: nm_sbindir,