build: use dolt

Drop-in replacement to libtool: http://dolt.freedesktop.org/. More
details: http://marc.info/?l=freedesktop-xorg&m=120791871615872&w=3

kmod is relatively fast to compile, so it doesn't matter much.
Nonetheless, less forks the better.

Compilation time using ./bootstrap-configure --disable-manpages and
make -j4

libtool
real    0m6.453s
user    0m21.067s
sys     0m0.773s

dolt
real    0m4.792s
user    0m15.920s
sys     0m0.637s
diff --git a/.gitignore b/.gitignore
index 58ef42a..aa02fbf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,6 +18,8 @@
 /configure
 /coverage
 /cov-int
+/doltcompile
+/doltlibtool
 /libtool
 /stamp-h1
 /test-suite.log