This fixes:

  $ make installer
  [...]
  (cd /tmp/qemu-nsis; \
           for i in qemu-system-*.exe; do \
             arch=${i%.exe}; \
             arch=${arch#qemu-system-}; \
             echo Section \"$arch\" Section_$arch; \
             echo SetOutPath \"\$INSTDIR\"; \
             echo File \"\${BINDIR}\\$i\"; \
             echo SectionEnd; \
           done \
          ) >/tmp/qemu-nsis/system-emulations.nsh
  makensis -V2 -NOCD \
                   \
                  -DCONFIG_GTK="y" \
                  -DBINDIR="/tmp/qemu-nsis" \
                   \
                  -DSRCDIR="/source/qemu" \
                  -DOUTFILE="qemu-setup-4.0.90.exe" \
                  -DDISPLAYVERSION="4.0.90" \
                  /source/qemu/qemu.nsi
  File: "/tmp/qemu-nsis\qemu-doc.html" -> no files found.
  Usage: File [/nonfatal] [/a] ([/r] [/x filespec [...]] filespec [...] |
     /oname=outfile one_file_only)
  Error in script "/source/qemu/qemu.nsi" on line 173 -- aborting creation process
  make: *** [Makefile:1080: qemu-setup-4.0.90.exe] Error 1

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
Not sure is this the only dependency missing, or this is the correct fix...

 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 1fcbaed62c..f8dac48981 100644
--- a/Makefile
+++ b/Makefile
@@ -1073,7 +1073,7 @@ installer: $(INSTALLER)
 
 INSTDIR=/tmp/qemu-nsis
 
-$(INSTALLER): $(SRC_PATH)/qemu.nsi
+$(INSTALLER): install-doc $(SRC_PATH)/qemu.nsi
 	$(MAKE) install prefix=${INSTDIR}
 ifdef SIGNCODE
 	(cd ${INSTDIR}; \
-- 
2.20.1