Executing cmake --install does not install compiler headers

### What happened?

The headers are not being installed as part of the installation process. The e.g. libIREECompiler.so lib is installed just fine.

Looking at the cmake generated install files, I can see it compares the component names with expected strings. For both of the `compiler/src/iree/compiler/API/cmake_install.cmake` (where the library is handled) and `compiler/bindings/c/cmake_install.cmake` (where the headers are handled) the `CMAKE_INSTALL_COMPONENT` variable is always empty. However, the former file contains instructions to check for an empty string and installs the library even if the component name is empty. The header related file does not have checks for empty names. So the headers are simply skipped during the installation process.

### Steps to reproduce your issue

1. Configure (my setup):
```
cmake -G Ninja -B ../iree-build -S . \
-DIREE_TARGET_BACKEND_ROCM=OFF \
-DIREE_TARGET_BACKEND_METAL_SPIRV=OFF \
-DIREE_CUDA_LIBDEVICE_PATH=/usr/lib/nvidia-cuda-toolkit/libdevice/libdevice.10.bc \
-DIREE_BUILD_DOCS=ON \
-DCMAKE_BUILD_TYPE=RelWithDebInfo \
-DIREE_ENABLE_ASSERTIONS=ON \
-DIREE_ENABLE_SPLIT_DWARF=ON \
-DIREE_ENABLE_LLD=ON \
-DIREE_BUILD_PYTHON_BINDINGS=ON \
-DPython3_EXECUTABLE="$(which python3)" \
-DCMAKE_INSTALL_PREFIX="${HOME}/.local" \
-DCMAKE_C_COMPILER=clang \
-DCMAKE_CXX_COMPILER=clang++ \
-DCMAKE_CUDA_COMPILER=nvcc \
-DCMAKE_C_COMPILER_LAUNCHER=ccache \
-DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
.
```

2. Build:
```
cmake --build ../iree-build
```

3. Install (no headers are installed, no `${HOME}/.local/include` is created):
```
cmake --install ../iree-build
```

### What component(s) does this issue relate to?

Compiler

### Version information

```
14895845b Adding iree-benchmark-executable help text for CUDA.
```

### Additional context

Meanwhile, the headers can be installed with `ninja` with no issues:
```
ninja -C ../iree-build iree-install-dist
```