🔨 Introduce QOLM_INSTALL to make installation optional

This option is enabled if QOlm is main project,
and disabled if QOlm isn't.
It is user responsibility to enable it when fetching QOlm if he needs to install it

CMakeLists.txt

@@ -36,6 +36,8 @@ set(QOLM_TESTS_PREFIX ${QOLM_PROJECT} CACHE STRING "Prefix for all QOlm tests")
 set(QOLM_ENABLE_EXAMPLES OFF CACHE BOOL "Create or not a target for examples")
 set(QOLM_EXAMPLES_PREFIX ${QOLM_PROJECT} CACHE STRING "Prefix for all QOlm tests")
 
+set(QOLM_INSTALL ${QOLM_MAIN_PROJECT} CACHE BOOL "Generate the install target")
+
 # ───── VERSION ─────
 
 set(QOLM_VERSION_MAJOR 3)
@@ -72,6 +74,7 @@ message(STATUS "QOLM_VERSION          : " ${QOLM_VERSION})
 message(STATUS "QOLM_VERSION_TAG      : " ${QOLM_VERSION_TAG})
 message(STATUS "QOLM_FOLDER_PREFIX    : " ${QOLM_FOLDER_PREFIX})
 message(STATUS "QOLM_BUILD_SHARED     : " ${QOLM_BUILD_SHARED})
+message(STATUS "QOLM_INSTALL          : " ${QOLM_INSTALL})
 
 # Tests
 message(STATUS "QOLM_ENABLE_TESTS     : " ${QOLM_ENABLE_TESTS})
@@ -146,23 +149,25 @@ if(QOLM_MAIN_PROJECT)
   include(cmake/PrintConfiguration.cmake)
 endif()
 
-include(GNUInstallDirs)
-install(TARGETS ${QOLM_TARGET}
-  EXPORT ${QOLM_TARGET}Targets
-  PUBLIC_HEADER DESTINATION include/QOlm
-)
+if(QOLM_INSTALL)
+  include(GNUInstallDirs)
+  install(TARGETS ${QOLM_TARGET}
+    EXPORT ${QOLM_TARGET}Targets
+    PUBLIC_HEADER DESTINATION include/QOlm
+  )
 
-export(EXPORT ${QOLM_TARGET}Targets
-  FILE "${CMAKE_CURRENT_BINARY_DIR}/${QATERIAL_TARGET}/${QOLM_TARGET}Targets.cmake"
-  NAMESPACE ${QOLM_TARGET}::
-)
+  export(EXPORT ${QOLM_TARGET}Targets
+    FILE "${CMAKE_CURRENT_BINARY_DIR}/${QATERIAL_TARGET}/${QOLM_TARGET}Targets.cmake"
+    NAMESPACE ${QOLM_TARGET}::
+  )
 
-set(ConfigPackageLocation lib/cmake/${QOLM_TARGET})
-install(EXPORT ${QOLM_TARGET}Targets
-  FILE
-  ${QOLM_TARGET}Targets.cmake
-  NAMESPACE
-  ${QOLM_TARGET}::
-  DESTINATION
-  ${ConfigPackageLocation}
-)
+  set(ConfigPackageLocation lib/cmake/${QOLM_TARGET})
+  install(EXPORT ${QOLM_TARGET}Targets
+    FILE
+    ${QOLM_TARGET}Targets.cmake
+    NAMESPACE
+    ${QOLM_TARGET}::
+    DESTINATION
+    ${ConfigPackageLocation}
+  )
+endif()