Rewrite the Compiler detection tests for deprecation and unused. Simplify and make more safe, clang or compilers supporting __has_extension() and __has_attribute() should work perfectly. There are now GCC version tests for all these features, however there seems to be some disagreement online about which GCC versions introduced these features, so I picked the versions that I felt had the highest consensus. Can revisit the specific versions if new information is available: unused attribute: GCC 3.1 (BSD seems to think 2.7) deprecated attribute: GCC 3.2 (Hedley seems to think 4.0) deprecated with message attribute: GCC 4.5

prefix=@prefix@
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${exec_prefix}/include
 
Name: dwindows
Description: Dynamic Windows Cross platform UI Toolkit
Version: @VERSION@
Libs: -L${prefix}/lib -ldwindows @LIBS@
Cflags: -I${prefix}/include @CFLAGS@ -D@DW_DEFINE@