compilers: Standardize the names of compiler options

Most options don't use language prefaced options (std vs c_std)
internally, as we don't need that due to namespacing. Let's do that
across the board

mesonbuild/compilers/c.py

@@ -615,7 +615,7 @@ class Xc16CCompiler(Xc16Compiler, CCompiler):
 
     def get_options(self) -> 'OptionDictType':
         opts = CCompiler.get_options(self)
-        opts.update({'c_std': coredata.UserComboOption('C language standard to use',
+        opts.update({'std': coredata.UserComboOption('C language standard to use',
                                                      ['none', 'c89', 'c99', 'gnu89', 'gnu99'],
                                                      'none')})
         return opts
@@ -660,7 +660,7 @@ class CompCertCCompiler(CompCertCompiler, CCompiler):
 
     def get_options(self) -> 'OptionDictType':
         opts = CCompiler.get_options(self)
-        opts.update({'c_std': coredata.UserComboOption('C language standard to use',
+        opts.update({'std': coredata.UserComboOption('C language standard to use',
                                                      ['none', 'c89', 'c99'],
                                                      'none')})
         return opts
@@ -698,7 +698,7 @@ class C2000CCompiler(C2000Compiler, CCompiler):
 
     def get_options(self) -> 'OptionDictType':
         opts = CCompiler.get_options(self)
-        opts.update({'c_std': coredata.UserComboOption('C language standard to use',
+        opts.update({'std': coredata.UserComboOption('C language standard to use',
                                                      ['none', 'c89', 'c99', 'c11'],
                                                      'none')})
         return opts

mesonbuild/compilers/cpp.py

@@ -790,7 +790,7 @@ class C2000CPPCompiler(C2000Compiler, CPPCompiler):
 
     def get_options(self) -> 'OptionDictType':
         opts = CPPCompiler.get_options(self)
-        opts.update({'cpp_std': coredata.UserComboOption('C++ language standard to use',
+        opts.update({'std': coredata.UserComboOption('C++ language standard to use',
                                                      ['none', 'c++03'],
                                                      'none')})
         return opts

mesonbuild/compilers/cuda.py

@@ -197,7 +197,7 @@ class CudaCompiler(Compiler):
 
     def get_options(self) -> 'OptionDictType':
         opts = super().get_options()
-        opts.update({'cuda_std': coredata.UserComboOption('C++ language standard to use',
+        opts.update({'std': coredata.UserComboOption('C++ language standard to use with cuda',
                                                      ['none', 'c++03', 'c++11', 'c++14'],
                                                      'none')})
         return opts
@@ -212,7 +212,7 @@ class CudaCompiler(Compiler):
         # the combination of CUDA version and MSVC version; the --std= is thus ignored
         # and attempting to use it will result in a warning: https://stackoverflow.com/a/51272091/741027
         if not is_windows():
-            std = options['cuda_std']
+            std = options['std']
             if std.value != 'none':
                 args.append('--std=' + std.value)