Notmuch fails to build with gmime 2.6.4

[hollunder at lavabit.com]

Hi there. I've seen gmime related discussion but it's hard to follow using
a web interface, so here's my bug report.

Arch Linux x86_64
gmime 2.6.4
notmuch git, last commit: 8ea82928b91e847298e4586f9db9734e727a418a

Build error:

CC -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector
--param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2 command-line-arguments.o
CC -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector
--param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2 debugger.o
In file included from debugger.c:21:0:
notmuch-client.h:72:5: error: unknown type name ‘GMimeSignatureValidity’
notmuch-client.h:86:5: error: unknown type name ‘GMimeCipherContext’
notmuch-client.h:297:5: error: unknown type name ‘GMimeSignatureValidity’
notmuch-client.h:322:3: error: unknown type name ‘GMimeCipherContext’
make: *** [debugger.o] Error 1

Regards,
Philipp