Display error if building for ARM architecture older than ARMv6

Chromium is only supported on ARMv6 and ARMv7 for ARM architecture.

Change-Id: I0493c9ba2baf4a537f759286622056093c0d4a25
Reviewed-by: Andras Becsi <andras.becsi@digia.com>

src/core/gyp_run.pro

@@ -61,6 +61,7 @@ cross_compile {
         !isEmpty(MARMV) {
             MARMV = $$split(MARMV,)
             MARMV = $$member(MARMV, 0)
+            lessThan(MARMV, 6): error("$$MARCH architecture is not supported")
             GYP_ARGS += "-D arm_version=\"$$MARMV\""
         }