make failure when building on cygwin.

[Stephen Smith <ischis2@xxxxxxx>]

I tried to build the 2.34.0 version on cygwin and received the following.  I 
am using commit 7e27bd589d328b9da.  the make utility is GNU Make 4.2.1

$  make prefix=/usr/local all html 
GIT_VERSION = 2.34.0.rc0.dirty 
GIT_VERSION = 2.34.0.rc0 
GIT_VERSION = 2.34.0.rc0.dirty 
GIT_VERSION = 2.34.0.rc0 
GIT_VERSION = 2.34.0.rc0.dirty 
GIT_VERSION = 2.34.0.rc0

I broke out of the build and and re-issued the make command at which point the 
code starts to build correctly.

This is just an FYI.