Make sure plugins on Linux resolve all dependencies

Remove the previous code which hardcoded options and didn't work for
linux-icc.

Reviewed-By: dt

qtcreator.pri

@@ -146,12 +146,6 @@ unix {
     UI_DIR = $${OUT_PWD}/.uic
 }
 
-linux-g++* {
-    # Bail out on non-selfcontained libraries. Just a security measure
-    # to prevent checking in code that does not compile on other platforms.
-    QMAKE_LFLAGS += -Wl,--allow-shlib-undefined -Wl,--no-undefined
-}
-
 win32-msvc* { 
     #Don't warn about sprintf, fopen etc being 'unsafe'
     DEFINES += _CRT_SECURE_NO_WARNINGS

src/qtcreatorplugin.pri

@@ -60,6 +60,7 @@ macx {
 contains(QT_CONFIG, reduce_exports):CONFIG += hide_symbols
 
 CONFIG += plugin plugin_with_soname
+linux*:QMAKE_LFLAGS += $$QMAKE_LFLAGS_NOUNDEF
 
 !macx {
     target.path = /$$IDE_LIBRARY_BASENAME/qtcreator/plugins/$$PROVIDER