add the correct input file to makeindex call


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11313 a1c6a512-1295-4272-9138-f99709370657
diff --git a/manual/LaTeX.Rules b/manual/LaTeX.Rules
index 7a397f3..fbcd460 100644
--- a/manual/LaTeX.Rules
+++ b/manual/LaTeX.Rules
@@ -116,6 +116,7 @@
 END_FILE  := $(shell ls $(DOCUMENT).end 2>/dev/null)
 TEX_FILES := $(DOCUMENT).tex
 OTHER_FILES := $(DOCUMENT).blg $(DOCUMENT).log $(DOCUMENT).out
+INDEX_ARGS := -s mkidx.ist
 
 # grab the contents of \bibliograph{} commands
 ifeq ($(BIB_FILES),)
@@ -255,7 +256,7 @@
 #
 
 %.ind : %.idx
-	makeindex $<
+	makeindex $(INDEX_ARGS) $<
 
 #
 # Generate a .aux or .idx file if it doesn't already exist.  The existance