capstone: Update to upstream "next" branch

This branch contains a number of improvements over master,
including making all of the disassembler data constant.

We are skipping past the 4.0 branchpoint, which changed
the location of the includes within the source directory.

Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

meson.build

@@ -802,6 +802,7 @@ if capstone_opt == 'internal'
       'capstone/arch/X86/X86DisassemblerDecoder.c',
       'capstone/arch/X86/X86ATTInstPrinter.c',
       'capstone/arch/X86/X86IntelInstPrinter.c',
+      'capstone/arch/X86/X86InstPrinterCommon.c',
       'capstone/arch/X86/X86Mapping.c',
       'capstone/arch/X86/X86Module.c'
     )
@@ -826,7 +827,7 @@ if capstone_opt == 'internal'
                                c_args: capstone_cargs,
                                include_directories: 'capstone/include')
   capstone = declare_dependency(link_with: libcapstone,
-                                include_directories: 'capstone/include')
+                                include_directories: 'capstone/include/capstone')
 endif
 config_host_data.set('CONFIG_CAPSTONE', capstone.found())