Relies on global flags set when the user ISR is executing.
Unclear if this fixes any bugs as ISR code may not have been calling
into LWIP, but the previous implementation was broken.
mbedTLS version 2.1.0 (current stable)
Has some known issues/hacks:
* Entropy source not hooked in at all
* Linker script has a messy hack in it to store some (not all) data in
irom
This fixes a long-standing bug where build directories sometimes
expanded many levels deeper than they should have.
Component names can now no longer contains slashes (ie the component
name for 'extras/i2c' is now just 'i2c')
* This fixes the problem of axTLS symbols hmac_md5/hmac_sha1 having same
name as symbols in libwpa (which have incompatible signatures)
* Also allows for easier identification and piece-by-piece removal of
binary functions.
* Some libc symbols are not renamed, list is in lib/symbols_norename.txt
