fix(core): Ensure correct function linkage for C/C++ compatibility

This commit fixes a critical linkage bug that caused "undefined reference"
errors when compiling with a C++ compiler (G++), even though the same
code compiled successfully with a C compiler (GCC).

The root cause is a divergence in how `inline` is handled by standard
C++ versus the common GNU C compiler dialect.

In C++, an `inline` function's symbol is not guaranteed to be emitted if
all its uses within a translation unit are successfully inlined. This
caused other object files, which needed to call the function, to fail at
the linking stage.

The C compilation was succeeding due to a non-standard GCC extension where
a plain `inline` definition also generates a linkable external symbol.
This behavior is not guaranteed by the C99/C11 standards and masked the
portability issue.

By removing the `inline` keyword from the function definition inside the
`#ifdef TEC_IMPL` block, the function becomes a standard, non-inline
function. This guarantees that one globally visible symbol is generated,
ensuring correct and portable linking for both C and C++ compilers.

REFERENCES:
- https://en.cppreference.com/w/c/language/inline.html
- https://en.cppreference.com/w/cpp/language/inline.html
- https://gcc.gnu.org/onlinedocs/gcc/Inline.html

Signed-off-by: Shashwat Agrawal <shashwatagrawal473@gmail.com>

Author: ShashwatAgrawal20

CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.10)
+project(tec.h C)
+
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -pedantic")
+
+include_directories(include)
+
+file(GLOB_RECURSE SRC_FILES "src/*.c")
+
+file(GLOB_RECURSE TEST_SOURCES "tests/*.c")
+
+list(FILTER SRC_FILES EXCLUDE REGEX ".*/main\\.c$")
+
+add_executable(main src/main.c ${SRC_FILES})
+add_executable(test_runner ${TEST_SOURCES} ${SRC_FILES})
+
+add_custom_target(test
+    COMMAND test_runner
+    DEPENDS test_runner
+    COMMENT "Running tests..."
+)

tec.h

@@ -564,7 +564,7 @@ extern "C" {
 
 tec_context_t tec_context = {};
 
-inline void TEC_POST_FAIL(void) {
+void TEC_POST_FAIL(void) {
     tec_context.current_failed++;
     tec_context.stats.failed_assertions++;
 #ifdef __cplusplus
@@ -575,7 +575,7 @@ inline void TEC_POST_FAIL(void) {
 #endif
 }
 
-inline void _tec_skip_impl(const char *reason, int line) {
+void _tec_skip_impl(const char *reason, int line) {
     const char *_reason = (reason);
     snprintf(tec_context.failure_message, TEC_MAX_FAILURE_MESSAGE_LEN,
              TEC_PRE_SPACE TEC_YELLOW TEC_ARROW_CHAR TEC_RESET