bug(linux): ibus-keyman does not build under clang

### Describe the bug

Ran `CC=clang CXX=clang++ ./build.sh build:linux`, and the build failed with the log attached. Without the `CC` and `CXX` environment variable, the build succeeds.
[log.txt](https://github.com/user-attachments/files/29969967/log.txt)

### Reproduce the bug

Ensure clang is installed. `CC=clang CXX=clang++ ./build.sh build:linux`

### Expected behavior

The build succeeds

### Related issues

_No response_

### Keyman apps

- [ ] Keyman for Android
- [ ] Keyman for iPhone and iPad
- [x] Keyman for Linux
- [ ] Keyman for macOS
- [ ] Keyman for Windows
- [ ] Keyman Developer
- [ ] KeymanWeb
- [ ] Other - give details at bottom of form

### Keyman version

19.0.255

### Operating system

Arch Linux

### Device

Asus Vivobook

### Target application

_No response_

### Browser

_No response_

### Keyboard name

_No response_

### Keyboard version

_No response_

### Language name

_No response_

### Additional context

_No response_

Start by reading the attached log.txt and reproducing the failure with `CC=clang CXX=clang++ ./build.sh build:linux` on Arch Linux. Then inspect the build.sh path involved in the failure; done means the Linux build completes successfully with Clang as well as without the compiler variables.

Written by the indexing model from the issue text.