Use .txt as the extension for syscall list file

Upstream uses .text, but this is rather unusual. Let's use .txt as the usual
suffix for text files. This tells various editors and such that the file should
be treated as plain text. I also want to a script to summarize license status,
and having an easy-to-recognize suffix makes this easier.

src/basic/meson.build

@@ -361,7 +361,7 @@ run_target(
         'update-syscall-tables',
         command : [syscall_table_update_sh, meson.current_source_dir()] + arch_list)
 
-syscall_names_text = files('syscall-names.text')
+syscall_list_txt = files('syscall-list.txt')
 
 syscall_lists = []
 foreach arch: arch_list

src/shared/meson.build

@@ -292,7 +292,7 @@ generate_syscall_list = find_program('generate-syscall-list.py')
 fname = 'syscall-list.h'
 syscall_list_h = custom_target(
         fname,
-        input : syscall_names_text,
+        input : syscall_list_txt,
         output : fname,
         command : [generate_syscall_list,
                    '@INPUT@'],

tools/syscall-table-update.sh

@@ -4,7 +4,7 @@ set -eu
 
 cd "$1" && shift
 
-curl --fail -L -o syscall-names.text 'https://raw.githubusercontent.com/hrw/syscalls-table/master/syscall-names.text'
+curl --fail -L -o syscall-list.txt 'https://raw.githubusercontent.com/hrw/syscalls-table/master/syscall-names.text'
 
 for arch in "$@"; do
     curl --fail -L -o syscalls-$arch "https://raw.githubusercontent.com/hrw/syscalls-table/master/tables/syscalls-$arch"