CHROMIUM: Add MAKEOPTS to portage list

MAKEOPTS is always set in the ebuild environment.

BUG=b:231476313
TEST=cros lint python-3.6.15.ebuild

Change-Id: I6cd48ecf3387a592fc87ace3f33b6c20ae85b546
diff --git a/src/ShellCheck/Data.hs b/src/ShellCheck/Data.hs
index 091f42e..cccf5fa 100644
--- a/src/ShellCheck/Data.hs
+++ b/src/ShellCheck/Data.hs
@@ -49,7 +49,7 @@
 portageManualInternalVariables = [
     -- toolchain settings
     "CFLAGS", "CXXFLAGS", "CPPFLAGS", "LDFLAGS", "FFLAGS", "FCFLAGS",
-    "CBUILD", "CHOST"
+    "CBUILD", "CHOST", "MAKEOPTS"
     -- TODO: Delete these if we can handle `tc-export CC` implicit export.
     , "CC", "CPP", "CXX"