make dist fails for directories with spaces in their name

[Paul Brannan]

I'm using automake 1.10 on cygwin where my home directory is "/home/Paul 
Brannan".  I have a project located in my home directory which uses 
automake.

I can build and install the project, however "make dist" fails, because 
it does not create the dist directory correctly.

Two changes are necessary to fix the problem:

- $distdir must be quoted whenever it is used
- The $(MKDIR_P) line in the distdir rule that creates the dist 
directory must be quoted as well.

I have worked around this bug by post-processing all my Makefile.in 
files after invoking automake.