.gitignore: update for meson conversion

This repository was converted from cmake to meson a while back now,
but the .gitignore file still contained a lot of cmake content.

  * Remove cmake-related content
  * Add meson-related content from other repositories as a
    reference (ex. phosphor-logging).
  * Leave IDE-related content alone.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ide3f11957f0b50c06d66ad794bca2ee932275ad3
diff --git a/.gitignore b/.gitignore
index b8078d3..2619269 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,26 +1,6 @@
-build
+build*/
+subprojects/*
+!subprojects/*.wrap
+
 .vscode
-toolchain.cmake
-Boost-prefix/
-CMakeCache.txt
-CMakeFiles/
-Makefile
-boost-src/
-cmake_install.cmake
-compile_commands.json
-nlohmann-json-src/
-nlohmann-json/
-sdbusplus-project/
-sdbusplus-src/
-adcsensor
-cpusensor
-exitairtempsensor
-fansensor
-hwmontempsensor
-intrusionsensor
-ipmbsensor
-mcutempsensor
-psusensor
 .idea/
-cmake-build-debug/
-sensors.cbp