Build: Use order-only prerequisites in lilypond-book chain rule.

The chain rule makes sure that only one instance of lilypond-book
is running at once. However, it also adds superficial dependencies
between manuals. We can avoid this using GNU make's order-only
syntax for prerequisites, which adds a pipe (|) character in front.

diff --git a/make/ly-rules.make b/make/ly-rules.make
index 0461e1b9c696c5c71fc738eb8e36b96512f76a29..418d1b9f03ac6cb47c03289acb71c82c260b8b82 100644 (file)
--- a/make/ly-rules.make
+++ b/make/ly-rules.make
@@ -9,9 +9,10 @@ $(outdir)/%.latex: %.doc $(INIT_LY_SOURCES) $(SCHEME_SOURCES)
 
 
 # This allows -j make option while making sure only one lilypond-book instance
-# is running at the same time
+# is running at the same time, using GNU make's order-only prerequisites so
+# as to not create superficial dependencies between unrelated manuals.
 define CHAIN_RULE
-$(i)
+| $(i)
 $(i): 
 endef