[.gitignore]: add build artifacts (#2938)

* [.gitignore]: add build artifacts

* Ignore images
* Ignore debug files
* Ignore compressed/tarred files
* Ignore libyang, smartmontools, and swig artifacts
* Ignore miscellaneous initramfs-tools artifacts

Signed-off-by: Lawrence Lee <t-lale@microsoft.com>

* [.gitignore]: update inclusion of dbg files
* Remove pattern '*dbg*' and replaced with '*-dbg' and '*dbg.j2'

Signed-off-by: Lawrence Lee <t-lale@microsoft.com>

.gitignore

@@ -9,6 +9,12 @@ target/
 *.deb
 *.changes
 *.buildinfo
+*.tar
+*.xz
+*.gz
+*-dbg
+*dbg.j2
+*.img
 
 # Subdirectories in src
 src/bash/*
@@ -43,6 +49,8 @@ src/libnl3/*
 !src/libnl3/Makefile
 src/libteam/*
 !src/libteam/Makefile
+src/libyang/*
+!src/libyang/Makefile
 src/lldpd/*
 !src/lldpd/Makefile
 !src/lldpd/patch/
@@ -59,6 +67,8 @@ src/radvd/*
 !src/radvd/patch/
 src/redis/*
 !src/redis/Makefile
+src/smartmontools/*
+!src/smartmontools/Makefile
 src/snmpd/*
 !src/snmpd/Makefile
 src/sonic-device-data/src/device/
@@ -66,6 +76,8 @@ src/sonic-device-data/src/debian/
 src/supervisor/*
 !src/supervisor/Makefile
 !src/supervisor/patch/
+src/swig/*
+!src/swig/Makefile
 src/telemetry/debian/*
 !src/telemetry/debian/changelog
 !src/telemetry/debian/compat
@@ -109,3 +121,7 @@ src/sonic-config-engine/sonic_config_engine.egg-info
 src/sonic-daemon-base/**/*.pyc
 src/sonic-daemon-base/build
 src/sonic-daemon-base/sonic_daemon_base.egg-info
+
+# Misc. files
+files/initramfs-tools/arista-convertfs
+files/initramfs-tools/union-mount