cmcurl: Use if(DEFINED) to simplify conditions

Replace old hacks of the form 'if("${VAR}" MATCHES "^${VAR}$")'
with the much simpler 'if(NOT DEFINED ${VAR})'.

Utilities/cmcurl/CMake/CurlCheckCSourceCompiles.cmake

@@ -13,7 +13,7 @@
 #  CMAKE_REQUIRED_LIBRARIES = list of libraries to link
 
 MACRO(CURL_CHECK_C_SOURCE_COMPILES SOURCE VAR)
-  IF("${VAR}" MATCHES "^${VAR}$" OR "${VAR}" MATCHES "UNKNOWN")
+  IF(NOT DEFINED ${VAR} OR ${VAR} MATCHES "UNKNOWN")
     SET(message "${VAR}")
     # If the number of arguments is greater than 2 (SOURCE VAR)
     IF(${ARGC} GREATER 2)
@@ -70,5 +70,5 @@ MACRO(CURL_CHECK_C_SOURCE_COMPILES SOURCE VAR)
         "${OUTPUT}\n"
         "Source file was:\n${src}\n")
     ENDIF(${VAR})
-  ENDIF("${VAR}" MATCHES "^${VAR}$" OR "${VAR}" MATCHES "UNKNOWN")
+  ENDIF()
 ENDMACRO(CURL_CHECK_C_SOURCE_COMPILES)

Utilities/cmcurl/CMakeLists.txt

@@ -505,7 +505,7 @@ ENDIF(NOT HAVE_SIGSETJMP)
 
 # For other curl specific tests, use this macro.
 MACRO(CURL_INTERNAL_TEST CURL_TEST)
-  IF("${CURL_TEST}" MATCHES "^${CURL_TEST}$")
+  IF(NOT DEFINED ${CURL_TEST})
     SET(MACRO_CHECK_FUNCTION_DEFINITIONS
       "-D${CURL_TEST} ${CMAKE_REQUIRED_FLAGS}")
     IF(CMAKE_REQUIRED_LIBRARIES)
@@ -533,7 +533,7 @@ MACRO(CURL_INTERNAL_TEST CURL_TEST)
         "Performing Curl Test ${CURL_TEST} failed with the following output:\n"
         "${OUTPUT}\n")
     ENDIF(${CURL_TEST})
-  ENDIF("${CURL_TEST}" MATCHES "^${CURL_TEST}$")
+  ENDIF()
 ENDMACRO(CURL_INTERNAL_TEST)
 
 # Do curl specific tests