[msitools] build-sys: Remove unneeded workaround

[Christophe Fergeau <teuf src gnome org>]

commit a4077a23a6161ac8f327356dac8b13ead6fc40f8
Author: Christophe Fergeau <cfergeau redhat com>
Date:   Tue Dec 1 10:55:49 2015 +0100

    build-sys: Remove unneeded workaround
    
    This is causing a build breakage when libmsi-1.0.pc isn't installed yet:
    
    $ make
      VALAC    libcommon_a_vala.stamp
      CC       tools/wixl/libcommon_a-util.o
      AR       libcommon.a
      VALAC    wixl_vala.stamp
    error: Package `libmsi-1.0' not found in specified Vala API directories or GObject-Introspection GIR 
directories
    Compilation failed: 1 error(s), 0 warning(s)
    Makefile:1110: recipe for target 'wixl_vala.stamp' failed
    make: *** [wixl_vala.stamp] Error 1

 Makefile.am |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 2789a51..867fd1a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -134,9 +134,6 @@ wixl_LDADD =                                        \
 # FIXME -j: automake valagen doesn't seem to wait deps:
 wixl_DEPENDENCIES = libmsi/libmsi.la common.vapi
 
-# FIXME: workaround for a vala bug 
-BUILT_SOURCES += wixl.h
-
 # Wixl-heat
 
 bin_PROGRAMS += wixl-heat