emu.sh: rename OPTLEVEL to PYOPT (to match variable name used in the C source)

docs/testing.md

@@ -39,7 +39,7 @@ python setup.py develop
 
 If you want to test against the emulator, run it in a separate terminal from the `trezor-core` checkout directory:
 ```sh
-OPTLEVEL=0 ./emu.sh
+PYOPT=0 ./emu.sh
 ```
 
 Find the device address and export it as an environment variable. For the emulator, this is:

emu.sh

@@ -3,12 +3,12 @@
 source emu.config 2>/dev/null
 
 EXE=build/unix/micropython
-OPTLEVEL="${OPTLEVEL:-1}"
+PYOPT="${PYOPT:-1}"
 MAIN="${MAIN:-main.py}"
 BROWSER="${BROWSER:-chromium}"
 HEAPSIZE="${HEAPSIZE:-800K}"
 
-ARGS="-O${OPTLEVEL} -X heapsize=${HEAPSIZE}"
+ARGS="-O${PYOPT} -X heapsize=${HEAPSIZE}"
 
 cd `dirname $0`/src