Added support for SRP based scheduling for armv6m

ui/v6m-interrupt-not-enough.rs_no

@@ -0,0 +1,54 @@
+//! v6m-interrupt-not-enough.rs_no (not run atm)
+//!
+//! Expected behavior:
+//! should pass
+//! > cargo build --example m0_perf_err  --target thumbv7m-none-eabi --release
+//!
+//! should fail
+//! > cargo build --example m0_perf_err  --target thumbv6m-none-eabi --release
+//! Compiling cortex-m-rtic v1.0.0 (/home/pln/rust/rtic/cortex-m-rtic)
+//! error[E0308]: mismatched types
+//! --> examples/m0_perf_err.rs:25:1
+//!  |
+//! 25 | #[rtic::app(device = lm3s6965)]
+//!  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected an array with a fixed size of 4 elements, found one with 5 elements
+//!  |
+//!  = note: this error originates in the attribute macro `rtic::app` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+#![deny(unsafe_code)]
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+use panic_semihosting as _;
+
+#[rtic::app(device = lm3s6965)]
+mod app {
+
+    use cortex_m_semihosting::debug;
+
+    #[shared]
+    struct Shared {}
+
+    #[local]
+    struct Local {}
+
+    #[init]
+    fn init(_: init::Context) -> (Shared, Local, init::Monotonics) {
+        (Shared {}, Local {}, init::Monotonics())
+    }
+
+    #[inline(never)]
+    #[idle]
+    fn idle(_cx: idle::Context) -> ! {
+        debug::exit(debug::EXIT_SUCCESS); // Exit QEMU simulator
+
+        loop {
+            cortex_m::asm::nop();
+        }
+    }
+
+    // priority to high for v6m
+    #[task(binds = GPIOA, priority = 5)]
+    fn t0(_cx: t0::Context) {}
+}