Patch #709178: remove -static option from cygwinccompiler

After some more reflection (and no negative feedback), I am reverting the
original patch and applying my version, cygwinccompiler.py-shared.diff,
instead.

My reasons are the following:

1. support for older toolchains is retained
2. support for new toolchains (i.e., ld -shared) is added

The goal of my approach is to avoid breaking older toolchains while adding
better support for newer ones.

cygwinccompiler.py

@@ -33,7 +33,17 @@ cygwin in no-cygwin mode).
 # * cygwin gcc 2.95.2/ld 2.10.90/dllwrap 2.10.90 works now
 #   - its dllwrap doesn't work, there is a bug in binutils 2.10.90
 #     see also http://sources.redhat.com/ml/cygwin/2000-06/msg01274.html
+#   - using gcc -mdll instead dllwrap doesn't work without -static because
+#     it tries to link against dlls instead their import libraries. (If
+#     it finds the dll first.)
+#     By specifying -static we force ld to link against the import libraries,
+#     this is windows standard and there are normally not the necessary symbols
+#     in the dlls.
 #   *** only the version of June 2000 shows these problems
+# * cygwin gcc 3.2/ld 2.13.90 works
+#   (ld supports -shared)
+# * mingw gcc 3.2/ld 2.13 works
+#   (ld supports -shared)
 
 # This module should be kept compatible with Python 1.5.2.
 
@@ -77,7 +87,7 @@ class CygwinCCompiler (UnixCCompiler):
                           self.ld_version,
                           self.dllwrap_version) )
 
-        # ld_version >= "2.10.90" should also be able to use
+        # ld_version >= "2.10.90" and < "2.13" should also be able to use
         # gcc -mdll instead of dllwrap
         # Older dllwraps had own version numbers, newer ones use the
         # same as the rest of binutils ( also ld )
@@ -87,13 +97,20 @@ class CygwinCCompiler (UnixCCompiler):
         else:
             self.linker_dll = "dllwrap"
 
+        # ld_version >= "2.13" support -shared so use it instead of
+        # -mdll -static
+        if self.ld_version >= "2.13":
+            shared_option = "-shared"
+        else:
+            shared_option = "-mdll -static"
+
         # Hard-code GCC because that's what this is all about.
         # XXX optimization, warnings etc. should be customizable.
         self.set_executables(compiler='gcc -mcygwin -O -Wall',
                              compiler_so='gcc -mcygwin -mdll -O -Wall',
                              linker_exe='gcc -mcygwin',
-                             linker_so=('%s -mcygwin -mdll' %
-                                        self.linker_dll))
+                             linker_so=('%s -mcygwin %s' %
+                                        (self.linker_dll, shared_option)))
 
         # cygwin and mingw32 need different sets of libraries
         if self.gcc_version == "2.91.57":
@@ -262,6 +279,13 @@ class Mingw32CCompiler (CygwinCCompiler):
 
         CygwinCCompiler.__init__ (self, verbose, dry_run, force)
 
+        # ld_version >= "2.13" support -shared so use it instead of
+        # -mdll -static
+        if self.ld_version >= "2.13":
+            shared_option = "-shared"
+        else:
+            shared_option = "-mdll -static"
+
         # A real mingw32 doesn't need to specify a different entry point,
         # but cygwin 2.91.57 in no-cygwin-mode needs it.
         if self.gcc_version <= "2.91.57":
@@ -272,8 +296,9 @@ class Mingw32CCompiler (CygwinCCompiler):
         self.set_executables(compiler='gcc -mno-cygwin -O -Wall',
                              compiler_so='gcc -mno-cygwin -mdll -O -Wall',
                              linker_exe='gcc -mno-cygwin',
-                             linker_so='%s -mno-cygwin -mdll %s'
-                                        % (self.linker_dll, entry_point))
+                             linker_so='%s -mno-cygwin %s %s'
+                                        % (self.linker_dll, shared_option,
+                                           entry_point))
         # Maybe we should also append -mthreads, but then the finished
         # dlls need another dll (mingwm10.dll see Mingw32 docs)
         # (-mthreads: Support thread-safe exception handling on `Mingw32')