Use custom assembly code instead of MSP GCC primitives for dINT()/eINT()
and all other functions that enable or disable interrupts
Ensure interrupts are enabled before going in low-power mode
Ensure only GIE bit is touched in splx_()
Merge pull request #2214 from rousselk/msp430-fix-intr

Msp430 misc interrupt-related fixes
make: change escaped quotation marks

The '""' pattern is used so that the variable can be processed as a string
after the preprocessors evaluation. Change to \"\" instead, so that single
quotes can be used externally. The extra quotation marks are unneeded.

Related to #2213