Backport mozilla plugin installer fixes [15547], [15548] and [15550].

configure.ac

@@ -5234,7 +5234,7 @@ AS_IF([test "x${enable_shared_libvlc}" = "x"], [enable_shared_libvlc=no])
 AM_CONDITIONAL(BUILD_SHARED, [test "${enable_shared_libvlc}" != "no"])
 AS_IF([test "${enable_shared_libvlc}" != "no" || test "${enable_libtool}" != "no"], [
   AC_DEFINE(HAVE_SHARED_LIBVLC, 1, [Define to 1 if libvlc is built as a shared library.])
-  FILE_LIBVLC_DLL="File libvlc.dll"],
+  FILE_LIBVLC_DLL="!define LIBVLC_DLL libvlc.dll"],
   FILE_LIBVLC_DLL="" )
 
 pic=no

vlc.win32.nsi.in

@@ -13,6 +13,8 @@
 !define PRODUCT_UNINST_ROOT_KEY "HKLM"
 !define PRODUCT_ID "{ea92ef52-afe4-4212-bacb-dfe9fca94cd6}"
 
+@FILE_LIBVLC_DLL@
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;
 ; General configuration ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -326,7 +328,9 @@ Section "Media player (required)" SEC01
 
   !insertmacro InstallFile vlc.exe
   !insertmacro InstallFile vlc.exe.manifest
-  @FILE_LIBVLC_DLL@
+  !ifdef LIBVLC_DLL
+  !insertmacro InstallFile ${LIBVLC_DLL}
+  !endif
   !insertmacro InstallFile *.txt
 
   !insertmacro InstallFolder plugins
@@ -442,6 +446,9 @@ Section /o "Mozilla plugin" SEC03
     StrCmp $R2 "" "${Index}-Loop" ""
 
     CopyFiles "$INSTDIR\mozilla\*" "$R2"
+    !ifdef LIBVLC_DLL
+    CopyFiles ${LIBVLC_DLL} "$R2"
+    !endif
     Goto "${Index}-Loop"
 
   "${Index}-End:"