Use verbose keywords in linker fragments

When using flip-link for stack overflow protection, it parses the linker
scripts/fragments for RAM memory addresses and expects the keywords
'ORIGIN' and 'LENGTH' to be used in its verbose form. Allow
friction-less integration of flip-link and this crate by using the
verbose form.

build.rs

@@ -169,11 +169,11 @@ This may be due to incorrect feature configuration in Cargo.toml or stm32f3xx-ha
     let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
     let mut file = File::create(out_dir.join("memory.x")).unwrap();
     writeln!(file, "MEMORY {{").unwrap();
-    writeln!(file, "    FLASH (rx) : o = 0x8000000, l = {}K", flash).unwrap();
+    writeln!(file, "    FLASH (rx) : ORIGIN = 0x8000000, LENGTH = {}K", flash).unwrap();
     if ccmram > 0 {
-        writeln!(file, "    CCMRAM (rwx) : o = 0x10000000, l = {}K", ccmram).unwrap();
+        writeln!(file, "    CCMRAM (rwx) : ORIGIN = 0x10000000, LENGTH = {}K", ccmram).unwrap();
     }
-    writeln!(file, "    RAM (rwx) : o = 0x20000000, l = {}K", ram).unwrap();
+    writeln!(file, "    RAM (rwx) : ORIGIN = 0x20000000, LENGTH = {}K", ram).unwrap();
     writeln!(file, "}}").unwrap();
     println!("cargo:rustc-link-search={}", out_dir.display());
 }