Remove .gitignore files in subdirectories

With meson we no longer have generated files messing up the tree, so we no
longer need these files.

man/.gitignore

@@ -1,4 +0,0 @@
-pipewire-monitor.1
-pipewire-monitor.1.xml
-pipewire.1
-pipewire.1.xml

po/.gitignore

@@ -1,11 +0,0 @@
-.intltool-merge-cache
-Makefile.in.in
-Makevars.template
-POTFILES
-Rules-quot
-boldquot.sed
-en@boldquot.header
-en@quot.header
-insert-header.sin
-quot.sed
-remove-potcdate.sin

src/daemon/.gitignore

@@ -1 +0,0 @@
-pipewire.desktop

src/pipewire/.gitignore

@@ -1,2 +0,0 @@
-enumtypes.c
-enumtypes.h