added cmake and meson/ninja build

CMakeLists.txt

@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.6)
+project(pwdgen)
+set(CMAKE_C_FLAGS "-Wall")
+
+add_executable(
+    pwdgen
+    src/main.c
+)
+
+install(TARGETS pwdgen DESTINATION bin)

meson.build

@@ -0,0 +1,7 @@
+project('pwdgen', 'c', default_options: 'c_args=-Wall')
+
+executable(
+  'pwdgen',
+  'src/main.c',
+  install: true,
+)