Set uname_S to Linux instead of detecting build machine.
Android before API 26 does not support sync_file_range.

diff --git a/config.mak.uname b/config.mak.uname
index 3e26bb074a..8135d42963 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -4,7 +4,7 @@
 # Microsoft's Safe Exception Handling in libraries (such as zlib).
 # Typically required for VS2013+/32-bit compilation on Vista+ versions.
 
-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 := $(shell sh -c 'uname -r 2>/dev/null || echo not')
@@ -56,7 +56,6 @@ ifeq ($(uname_S),Linux)
 	HAVE_DEV_TTY = YesPlease
 	HAVE_CLOCK_GETTIME = YesPlease
 	HAVE_CLOCK_MONOTONIC = YesPlease
-	HAVE_SYNC_FILE_RANGE = YesPlease
 	HAVE_GETDELIM = YesPlease
 	FREAD_READS_DIRECTORIES = UnfortunatelyYes
 	HAVE_SYSINFO = YesPlease