Set uname_S to Linux instead of detecting build machine.
Android does not support -lrt.

diff -u -r ../git-2.10.0/config.mak.uname ./config.mak.uname
--- ../git-2.10.0/config.mak.uname	2016-09-02 21:59:09.000000000 -0400
+++ ./config.mak.uname	2016-09-03 17:27:41.964893344 -0400
@@ -1,6 +1,6 @@
 # Platform specific Makefile tweaks based on uname detection
 
-uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
+uname_S := Linux
 uname_M := $(shell sh -c 'uname -m 2>/dev/null || echo not')
 uname_O := $(shell sh -c 'uname -o 2>/dev/null || echo not')
 uname_R := $(shell sh -c 'uname -r 2>/dev/null || echo not')
@@ -36,8 +36,6 @@
 	HAVE_DEV_TTY = YesPlease
 	HAVE_CLOCK_GETTIME = YesPlease
 	HAVE_CLOCK_MONOTONIC = YesPlease
-	# -lrt is needed for clock_gettime on glibc <= 2.16
-	NEEDS_LIBRT = YesPlease
 	HAVE_GETDELIM = YesPlease
 	SANE_TEXT_GREP=-a
 endif