feat: don't build when used as FetchContent dependency.

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

Author: ShashwatAgrawal20

CMakeLists.txt

@@ -1,22 +1,21 @@
 cmake_minimum_required(VERSION 3.10)
 project(tec.h C)
-
-set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD 23)
 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} ${SRC_FILES})
+if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
+    file(GLOB_RECURSE SRC_FILES "src/*.c")
+    file(GLOB_RECURSE TEST_SOURCES "tests/*.c")
+    list(FILTER SRC_FILES EXCLUDE REGEX ".*/main\\.c$")
 
-add_custom_target(test
-    COMMAND test_runner
-    DEPENDS test_runner
-    COMMENT "Running tests..."
-)
+    add_executable(main src/main.c ${SRC_FILES})
+    add_executable(test_runner ${TEST_SOURCES} ${SRC_FILES})
+    add_custom_target(build_tests
+        COMMAND test_runner
+        DEPENDS test_runner
+        COMMENT "Running tests..."
+    )
+else()
+    message(STATUS "tec.h: Header-only library (skipping executables)")
+endif()