translate-c: handle string concatenation of function calls

[willnode]

Zig Version

0.12.0-dev.3366+8e7d9afda

Steps to Reproduce and Observed Behavior

# See https://github.com/willnode/summon/tree/a246528
git clone https://github.com/willnode/summon.git -b try-zig
cd summon
make install-nginx
zig build

install
└─ install summon
   └─ zig build-lib summon Debug native 3 errors
/home/willnode/summon/zig-cache/o/9f471bc5f7934470be5987871f47d714/cimport.zig:4488:11: error: opaque types have unknown size and therefore cannot be directly embedded in structs
    file: ngx_file_t = @import("std").mem.zeroes(ngx_file_t),
          ^~~~~~~~~~
/home/willnode/summon/zig-cache/o/9f471bc5f7934470be5987871f47d714/cimport.zig:3047:31: note: opaque declared here
pub const struct_ngx_file_s = opaque {};
                              ^~~~~~~~~
/home/willnode/summon/zig-cache/o/9f471bc5f7934470be5987871f47d714/cimport.zig:5842:36: error: unable to translate C expr: unexpected token 'a string literal'
pub const NGX_MODULE_SIGNATURE_0 = @compileError("unable to translate C expr: unexpected token 'a string literal'"); // /home/willnode/summon/nginx-1.22.1/src/core/ngx_module.h:21:9
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/main.zig:24:13: error: non-extern variable with opaque type 'cimport.struct_ngx_buf_s'
    var b: c.ngx_buf_t = undefined;
           ~^~~~~~~~~~
/home/willnode/summon/zig-cache/o/9f471bc5f7934470be5987871f47d714/cimport.zig:3049:30: note: opaque declared here
pub const struct_ngx_buf_s = opaque {};
                             ^~~~~~~~~
error: the following command failed with 3 compilation errors:
/home/willnode/.local/opt/zig-v0.12.0-dev.3366+8e7d9afda/zig build-lib -ODebug -I /home/willnode/summon/nginx-1.22.1/objs -I /home/willnode/summon/nginx-1.22.1/src/mail -I /home/willnode/summon/nginx-1.22.1/src/os/unix -I /home/willnode/summon/nginx-1.22.1/src/os -I /home/willnode/summon/nginx-1.22.1/src/event/modules -I /home/willnode/summon/nginx-1.22.1/src/event -I /home/willnode/summon/nginx-1.22.1/src/stream -I /home/willnode/summon/nginx-1.22.1/src/http/v2 -I /home/willnode/summon/nginx-1.22.1/src/http/modules/perl -I /home/willnode/summon/nginx-1.22.1/src/http/modules -I /home/willnode/summon/nginx-1.22.1/src/http -I /home/willnode/summon/nginx-1.22.1/src/core -I /home/willnode/summon/nginx-1.22.1/src/misc -I /home/willnode/summon/nginx-1.22.1/objs/src/mail -I /home/willnode/summon/nginx-1.22.1/objs/src/os/unix -I /home/willnode/summon/nginx-1.22.1/objs/src/os -I /home/willnode/summon/nginx-1.22.1/objs/src/event/modules -I /home/willnode/summon/nginx-1.22.1/objs/src/event -I /home/willnode/summon/nginx-1.22.1/objs/src/stream -I /home/willnode/summon/nginx-1.22.1/objs/src/http/v2 -I /home/willnode/summon/nginx-1.22.1/objs/src/http/modules/perl -I /home/willnode/summon/nginx-1.22.1/objs/src/http/modules -I /home/willnode/summon/nginx-1.22.1/objs/src/http -I /home/willnode/summon/nginx-1.22.1/objs/src/core -I /home/willnode/summon/nginx-1.22.1/objs/src/misc -Mroot=/home/willnode/summon/src/main.zig -lc --cache-dir /home/willnode/summon/zig-cache --global-cache-dir /home/willnode/.cache/zig --name summon -dynamic --listen=- 
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install summon transitive failure
   └─ zig build-lib summon Debug native 3 errors
error: the following build command failed with exit code 1:
/home/willnode/summon/zig-cache/o/a9ce6dcf4254ec6f5921d0f7e1cffe37/build /home/willnode/.local/opt/zig-v0.12.0-dev.3366+8e7d9afda/zig /home/willnode/summon /home/willnode/summon/zig-cache /home/willnode/.cache/zig --seed 0x1b9ba675 -Z53dd1933cc77c915

Expected Behavior

Library should be successfully compiled

[Vexu]

The first and third errors are #1499

The second reduces to a (somewhat) simple to implement missing feature:

#define bar() ""
#define FOO bar() "," bar()
// #define FOO bar "," bar