Eliminate && from Makefile recipes - totally unnecessary.

Justification: increases recipes' portability, notably on Win95.

Split out from #176, since @bulk88 disagrees: https://github.com/Perl-Toolchain-Gang/ExtUtils-MakeMaker/pull/168#issuecomment-67590474 and https://github.com/Perl-Toolchain-Gang/ExtUtils-MakeMaker/pull/176#issuecomment-67891163.