Add --nmagic linker arg, for unaligned flash origin support.

Without this, the linker places some extra program header entries that can confuse flashing tools.

Many thanks to @jonas-schievink for pointing me to this flag in Matrix.

.cargo/config

@@ -10,6 +10,10 @@
 # runner = "gdb -q -x openocd.gdb"
 
 rustflags = [
+  # This is needed if your flash or ram addresses are not aligned to 0x10000 in memory.x
+  # See https://github.com/rust-embedded/cortex-m-quickstart/pull/95
+  "-C", "link-arg=--nmagic",
+
   # LLD (shipped with the Rust toolchain) is used as the default linker
   "-C", "link-arg=-Tlink.x",