Avoid trailing spaces.

* data/c.m4: b4_comment(TEXT): Don't indent empty lines.
	* data/lalr1.cc: Don't indent before rule and symbol actions, as
	they can be empty, and anyway this incorrectly indents the first
	action.

data/c.m4

@@ -23,9 +23,12 @@
 
 # b4_comment(TEXT)
 # ----------------
+# Put TEXT in comment.  Avoid trailing spaces: don't indent empty lines.
+# Avoid adding indentation to the first line, as the indentation comes
+# from "/*".  That's why we don't patsubst([$1], [^\(.\)], [   \1]).
 m4_define([b4_comment], [/* m4_bpatsubst([$1], [
-], [
-   ])  */])
+\(.\)], [
+   \1])  */])
 
 # b4_identification
 # -----------------