Use ninja in dockerfiles

We are using alt's docker images based on alpine:edge. As of today (Oct
31, 2020), strange errors began to come from cmake/make.

```
 -- Check for working C compiler: /usr/bin/cc
 -- Check for working C compiler: /usr/bin/cc - broken
 CMake Error at /usr/share/cmake/Modules/CMakeTestCCompiler.cmake:66 (message):
   The C compiler

     "/usr/bin/cc"

   is not able to compile a simple test program.

   It fails with the following output:

     Change Dir: /app/CMakeFiles/CMakeTmp

     Run Build Command(s):/usr/bin/make cmTC_49c71/fast && /usr/bin/make  -f CMakeFiles/cmTC_49c71.dir/build.make CMakeFiles/cmTC_49c71.dir/build
     make: /usr/bin/make: Operation not permitted
     make: *** [Makefile:140: cmTC_49c71/fast] Error 127

   CMake will not be able to correctly generate this project.
 Call Stack (most recent call first):
   CMakeLists.txt:2 (project)
```

However, ninja builds seem fine. In the alpine:edge they have the
samurai[1] implementation of ninja. Let's use that as a workaround.

[1] https://pkgs.alpinelinux.org/package/edge/main/x86_64/samurai
5 jobs from 36-latex-converter in 7 seconds (queued for 1 second)
Status Job ID Name Coverage
  Prepare
canceled #193838
prepare:activemqcpp

00:00:07

 
  Build
canceled #193840
build:webui

canceled #193839
build:worker

 
  Test
canceled #193842
test:webui

canceled #193841
test:worker