autoconf: Trailing whitespace in Make Macros

1 
1 12.14 Trailing whitespace in Make Macros
1 ========================================
1 
1 GNU `make' 3.80 mistreats trailing whitespace in macro substitutions
1 and appends another spurious suffix:
1 
1      empty =
1      foo = bar $(empty)
1      print: ; @echo $(foo:=.test)
1 
1 prints `bar.test .test'.
1 
1    BSD and Solaris `make' implementations do not honor trailing
1 whitespace in macro definitions as Posix requires:
1 
1      foo = bar # Note the space after "bar".
1      print: ; @echo $(foo)t
1 
1 prints `bart' instead of `bar t'.  To work around this, you can use a
1 helper macro as in the previous example.
1