Failed to build on Windows with MSYS2

### What happened?
```
$ cmake --build .
[1/3] Building C object driver/common/CMakeFiles/adbc_driver_common.dir/utils.c.obj
FAILED: driver/common/CMakeFiles/adbc_driver_common.dir/utils.c.obj
C:\msys\ucrt64\bin\cc.exe -ID:/Github/arrow-adbc/c/include -ID:/Github/arrow-adbc/c/vendor -std=gnu99 -Wall -Wextra -Wpedantic -Werror -Wno-unused-parameter -Wno-maybe-uninitialized -MD -MT driver/common/CMakeFiles/adbc_driver_common.dir/utils.c.obj -MF driver\common\CMakeFiles\adbc_driver_common.dir\utils.c.obj.d -o driver/common/CMakeFiles/adbc_driver_common.dir/utils.c.obj -c D:/Github/arrow-adbc/c/driver/common/utils.c
In file included from D:/Github/arrow-adbc/c/driver/common/utils.h:25,
from D:/Github/arrow-adbc/c/driver/common/utils.c:18:
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:304:1: error: 'dllimport' attribute ignored [-error=attributes]
304 | };
| ^
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:357:1: error: 'dllimport' attribute ignored [-error=attributes]
357 | };
| ^
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:815:1: error: 'dllimport' attribute ignored [-error=attributes]
815 | };
| ^
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:838:1: error: 'dllimport' attribute ignored [-error=attributes]
838 | };
| ^
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:877:1: error: 'dllimport' attribute ignored [-error=attributes]
877 | };
| ^
D:/Github/arrow-adbc/c/include/arrow-adbc/adbc.h:1086:1: error: 'dllimport' attribute ignored [-error=attributes]
1086 | };
| ^
cc1.exe: all warnings being treated as errors
ninja: build stopped: subcommand failed.
```

### Stack Trace

### How can we reproduce the bug?

The commands to reproduce the bug
```
cd arrow-adbc/c
mkdir build
cd build
cmake ..
cmake --build .
```

### Environment/Setup

- Windows: Windows 11 23H2 (22631.4460) Windows Feature Experience Pack 1000.22700.1047.0
- MSYS2: GCC 14.2

Reproduce the failure from the c directory with the listed CMake commands under Windows/MSYS2, then inspect c/include/arrow-adbc/adbc.h and the common driver files named in the build output. Done means the MSYS2 build completes without the dllimport warnings being promoted to errors.

Written by the indexing model from the issue text.