vmtest: kbuild: add CONFIG_MODULE_UNLOAD=y

I currently have no idea whether the test kmod can actually unload
successfully because the vmtest kernels don't support unloading modules.
It might also be useful to test unloading other modules in the future.

Signed-off-by: Omar Sandoval <osandov@osandov.com>

vmtest/kbuild.py

@@ -30,7 +30,7 @@ class KernelFlavor(NamedTuple):
     config: str
 
     def localversion(self) -> str:
-        localversion = "-vmtest13"
+        localversion = "-vmtest14"
         # The default flavor should be the "latest" version.
         localversion += ".1" if self.name == "default" else ".0"
         localversion += self.name
@@ -81,6 +81,7 @@ def kconfig(flavor: KernelFlavor) -> str:
 CONFIG_EXPERT=y
 {flavor.config}
 CONFIG_MODULES=y
+CONFIG_MODULE_UNLOAD=y
 CONFIG_CC_OPTIMIZE_FOR_SIZE=y
 
 # We run the tests in KVM.