Use same version in <linux/version.h> and uname()

We had a different Linux version compiled into uname() (3.7.0) than
we had compiled into other code (via <linux/version.h>).

This patch makes them both pretend to be 3.7.0 - arbitrarily chosen
as the current Linux version at the time OSv was created. The new code
verifies with a static assertion that both files contain the same version,
so if they diverge, uname.c will fail compilation.

Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>

include/glibc-compat/linux/version.h

-#define LINUX_VERSION_CODE 198669
+#define LINUX_VERSION_CODE 198400
 #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))

libc/misc/uname.c

@@ -8,10 +8,25 @@
 #include <sys/utsname.h>
 #include <string.h>
 
+// The Linux version we're pretending to be
+#define LINUX_MAJOR 3
+#define LINUX_MINOR 7
+#define LINUX_PATCH 0
+
+// Verify that the version defined in <linux/version.h> is the same
+#include <linux/version.h>
+_Static_assert(KERNEL_VERSION(LINUX_MAJOR, LINUX_MINOR, LINUX_PATCH)
+        == LINUX_VERSION_CODE,
+        "LINUX_VERSION_CODE in include/glibc-compat/linux/version.h "
+        "does not match version in libc/misc/uname.c");
+
+#define str(s) #s
+#define str2(s) str(s)
+
 struct utsname utsname = {
 	.sysname	= "Linux",	/* lie, to avoid confusing the payload. */
 	.nodename	= "osv.local",
-	.release	= "3.7",
+	.release	= str2(LINUX_MAJOR) "." str2(LINUX_MINOR) "." str2(LINUX_PATCH),
 	.version	= "#1 SMP",
 	.machine	= "x86_64",
 };