Description

This PR resolves a potential memory leak identified via static analysis in the Linux backend. It also implements several IWYU header fixes.

Problems Identified

1. Linux Memory Leak: There is a potential memory leak in linux/hid.c parse_uevent_info where multiple matching HID_UNIQ or HID_NAME keys in a uevent file could overwrite previously allocated buffers without freeing them first.
2. Transitive Include Fragility: Several source files (libusb/hid.c and mac/hid.c) relied on transitive inclusions for standard types like uint8_t, standard functions like calloc, and error definitions like errno. If parent headers are refactored, these sources will break.
3. Unused Headers: Unused headers (such as <sys/utsname.h> and <linux/version.h>) were included in multiple places, unnecessarily increasing compile times.

Proposed Changes

• Linux Memory Leak Fix
  • Updated the Linux backend linux/hid.c to safely free any previously allocated memory before saving a new device property. This stops memory from leaking if a device's info key (like name or serial) is parsed more than once.
• IWYU (Include-What-You-Use) Header Cleanups
  • Added missing headers (like <stdint.h>, <stdlib.h>, and <errno.h>) across the test utility, macOS, and LibUSB backends so they don't crash or break when parent files are updated.
  • Removed unused headers (like <sys/utsname.h> and <linux/version.h> ) that were cluttering the code and slowing down compile times.

Verification & Testing

1. Automated Compilation

Clean out-of-source builds were configured and executed using CMake:

cmake -B build -S . -DHIDAPI_WITH_LIBUSB=OFF -DHIDAPI_BUILD_HIDTEST=ON
cmake --build build

• Result: All targets compiled with zero warnings and zero errors.

2. Static Analysis

A verification pass using clang-tidy was conducted on the Linux backend:

clang-tidy -p build-tidy linux/hid.c

• Result: The Potential memory leak warning has been successfully resolved.

3. Functional Verification

The compiled test utility hidtest_hidraw was run successfully. It executed the hid_enumerate() discovery loop using our modified parse_uevent_info implementation, successfully extracting and displaying all connected USB device attributes