treewide: internally avoid deprecated machine file uses of "pkgconfig"

We support this in a machine file:

```
[binaries]
pkgconfig = 'pkg-config'
pkg-config = 'pkg-config'
```

and you can use either one, because internally we look up both. If you
only set *one* of them, this plays awkwardly with setting $PKG_CONFIG,
since we don't know which one you set in the machine file and the
*other* one will be initialized from the environment instead.

In commit 22df45a we changed program
lookup of config-tool style dependencies to use the regular tool names
and only fall back on the strange internal names. This affected the
pkg-config class too.

The result is that instead of preferring `pkgconfig =` followed by
$PKG_CONFIG followed by `pkg-config =`, we inverted the lookup order.
This is a good idea anyway, because now it behaves consistently with
`find_program('pkg-config')`.

Unfortunately, we documented the wrong name in a bunch of places, and
also used the wrong name in various testsuite bits, which meant that if
you set $PKG_CONFIG and then ran the testsuite, it would fail.

Correct these references, because they are buggy.

cross/armclang-linux.txt

@@ -22,7 +22,7 @@ c = ['/opt/arm/developmentstudio-2019.0/sw/ARMCompiler6.12/bin/armclang', '--tar
 #cpp = '/usr/bin/arm-linux-gnueabihf-g++'
 ar = '/opt/arm/developmentstudio-2019.0/sw/ARMCompiler6.12/bin/armar'
 #strip = '/usr/arm-linux-gnueabihf/bin/strip'
-#pkgconfig = '/usr/bin/arm-linux-gnueabihf-pkg-config'
+#pkg-config = '/usr/bin/arm-linux-gnueabihf-pkg-config'
 
 [host_machine]
 system = 'baremetal'

cross/linux-mingw-w64-32bit.txt

@@ -4,7 +4,7 @@ cpp = '/usr/bin/i686-w64-mingw32-g++'
 objc = '/usr/bin/i686-w64-mingw32-gcc'
 ar = '/usr/bin/i686-w64-mingw32-ar'
 strip = '/usr/bin/i686-w64-mingw32-strip'
-pkgconfig = '/usr/bin/i686-w64-mingw32-pkg-config'
+pkg-config = '/usr/bin/i686-w64-mingw32-pkg-config'
 windres = '/usr/bin/i686-w64-mingw32-windres'
 exe_wrapper = 'wine'
 ld = '/usr/bin/i686-w64-mingw32-ld'

cross/linux-mingw-w64-64bit.txt

@@ -4,7 +4,7 @@ cpp = '/usr/bin/x86_64-w64-mingw32-g++'
 objc = '/usr/bin/x86_64-w64-mingw32-gcc'
 ar = '/usr/bin/x86_64-w64-mingw32-ar'
 strip = '/usr/bin/x86_64-w64-mingw32-strip'
-pkgconfig = '/usr/bin/x86_64-w64-mingw32-pkg-config'
+pkg-config = '/usr/bin/x86_64-w64-mingw32-pkg-config'
 windres = '/usr/bin/x86_64-w64-mingw32-windres'
 exe_wrapper = 'wine'
 cmake = '/usr/bin/cmake'

cross/none.txt

@@ -15,5 +15,5 @@ fc = ['false']
 objc = ['false']
 objcpp = ['false']
 ar = ['false']
-pkgconfig = ['false']
+pkg-config = ['false']
 cmake = ['false']

cross/ubuntu-armhf.txt

@@ -6,7 +6,7 @@ cpp = ['/usr/bin/arm-linux-gnueabihf-g++']
 rust = ['rustc', '--target', 'arm-unknown-linux-gnueabihf', '-C', 'linker=/usr/bin/arm-linux-gnueabihf-gcc-7']
 ar = '/usr/arm-linux-gnueabihf/bin/ar'
 strip = '/usr/arm-linux-gnueabihf/bin/strip'
-pkgconfig = '/usr/bin/arm-linux-gnueabihf-pkg-config'
+pkg-config = '/usr/bin/arm-linux-gnueabihf-pkg-config'
 ld = '/usr/bin/arm-linux/gnueabihf-ld'
 
 [built-in options]

docs/markdown/Machine-files.md

@@ -90,7 +90,7 @@ arch = 'aarch64-linux-gnu'
 c = arch + '-gcc'
 cpp = arch + '-g++'
 strip = arch + '-strip'
-pkgconfig = arch + '-pkg-config'
+pkg-config = arch + '-pkg-config'
 ...
 ```
 
@@ -165,7 +165,7 @@ c_ld = 'gold'
 cpp_ld = 'gold'
 ar = '/usr/i586-mingw32msvc/bin/ar'
 strip = '/usr/i586-mingw32msvc/bin/strip'
-pkgconfig = '/usr/bin/i586-mingw32msvc-pkg-config'
+pkg-config = '/usr/bin/i586-mingw32msvc-pkg-config'
 ```
 
 An incomplete list of internally used programs that can be overridden
@@ -179,7 +179,7 @@ here is:
 - libwmf-config
 - llvm-config
 - pcap-config
-- pkgconfig
+- pkg-config
 - sdl2-config
 - wx-config (or wx-3.0-config or wx-config-gtk)
 

mesonbuild/scripts/env2mfile.py

@@ -213,7 +213,7 @@ def detect_cross_debianlike(options: T.Any) -> MachineInfo:
     except ValueError:
         pass
     try:
-        infos.binaries['pkgconfig'] = locate_path("%s-pkg-config" % host_arch)
+        infos.binaries['pkg-config'] = locate_path("%s-pkg-config" % host_arch)
     except ValueError:
         pass # pkg-config is optional
     try:

test cases/unit/33 cross file overrides always args/ubuntu-armhf-overrides.txt

@@ -6,7 +6,7 @@ cpp = '/usr/bin/arm-linux-gnueabihf-g++'
 rust = ['rustc', '--target', 'arm-unknown-linux-gnueabihf', '-C', 'linker=/usr/bin/arm-linux-gnueabihf-gcc-7']
 ar = '/usr/arm-linux-gnueabihf/bin/ar'
 strip = '/usr/arm-linux-gnueabihf/bin/strip'
-pkgconfig = '/usr/bin/arm-linux-gnueabihf-pkg-config'
+pkg-config = '/usr/bin/arm-linux-gnueabihf-pkg-config'
 
 [properties]
 root = '/usr/arm-linux-gnueabihf'

test cases/unit/36 exe_wrapper behaviour/broken-cross.txt

@@ -3,7 +3,7 @@ c = '/usr/bin/x86_64-w64-mingw32-gcc'
 cpp = '/usr/bin/x86_64-w64-mingw32-g++'
 ar = '/usr/bin/x86_64-w64-mingw32-ar'
 strip = '/usr/bin/x86_64-w64-mingw32-strip'
-pkgconfig = '/usr/bin/x86_64-w64-mingw32-pkg-config'
+pkg-config = '/usr/bin/x86_64-w64-mingw32-pkg-config'
 windres = '/usr/bin/x86_64-w64-mingw32-windres'
 exe_wrapper = 'broken'
 

unittests/allplatformstests.py

@@ -2722,7 +2722,7 @@ def test_native_dep_pkgconfig(self):
         with tempfile.NamedTemporaryFile(mode='w', delete=False, encoding='utf-8') as crossfile:
             crossfile.write(textwrap.dedent(
                 '''[binaries]
-                pkgconfig = '{}'
+                pkg-config = '{}'
 
                 [properties]
 
@@ -2749,7 +2749,7 @@ def test_pkg_config_libdir(self):
         with tempfile.NamedTemporaryFile(mode='w', delete=False, encoding='utf-8') as crossfile:
             crossfile.write(textwrap.dedent(
                 '''[binaries]
-                pkgconfig = 'pkg-config'
+                pkg-config = 'pkg-config'
 
                 [properties]
                 pkg_config_libdir = ['{}']