package/dovecot: not available on static-only build

package/dovecot: not available on static-only build

Fixes
http://autobuild.buildroot.net/results/53f/53fd9003a4cf7d128f4d64d43209fe26d859a829/

http://autobuild.buildroot.net/results/53f/53fd9003a4cf7d128f4d64d43209fe26d859a829/dovecot-2.2.16/config.log
shows this pthread related link error during configure

sqlite3.c:(.text+0x5106): undefined reference to `pthread_mutex_trylock'
/home/test/autobuild/instance-2/output/host/usr/i686-buildroot-linux-uclibc/sysroot/usr/lib/libsqlite3.a(sqlite3.o): In function `pthreadMutexAlloc':
sqlite3.c:(.text+0x91fb): undefined reference to `pthread_mutexattr_init'
sqlite3.c:(.text+0x9205): undefined reference to `pthread_mutexattr_settype'
sqlite3.c:(.text+0x920e): undefined reference to `pthread_mutex_init'
sqlite3.c:(.text+0x9216): undefined reference to `pthread_mutexattr_destroy'
sqlite3.c:(.text+0x9234): undefined reference to `pthread_mutex_init'

Trying to fix it in dovecot.mk by

+# dovecot forgets to compile/link with -pthread breaking static linking
+DOVECOT_CONF_ENV += CFLAGS="$(TARGET_CFLAGS) -pthread" LIBS="-pthread"

results in a build error later on
setresgid.c:(.text+0x0): multiple definition of `setresgid'

which might be fixed in uclibc by porting
http://git.buildroot.net/buildroot/tree/package/uclibc/1.0.2/0001-fix-static-linking-of-pthread-apps.patch

but, at the end, I think it is better to not build Dovecot as a static
binary since it is heavy modularized and not worth the effort. Therefore
remove two patches fixing static linking, since they are not needed anymore.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>