Fixes for Windows cross-compilation

These days mingw by default produces binaries that depend on
libgcc-sjlj-1.dll, which defeats the whole historical point of mingw
(produce vanilla win32 binaries with no GNU stuff).

Add a hack to link with -static-libgcc, which avoids the problem.

Author: matteo-frigo

Makefile.am

@@ -131,10 +131,10 @@ libfftw3@PREC_SUFFIX@_la_LIBADD =			\
 
 if QUAD
 # cannot use -no-undefined since dependent on libquadmath
-libfftw3@PREC_SUFFIX@_la_LDFLAGS = -version-info @SHARED_VERSION_INFO@
+libfftw3@PREC_SUFFIX@_la_LDFLAGS = -version-info @SHARED_VERSION_INFO@ $(ENVIRONMENT_LIBFFTW3_LDFLAGS)
 else
 libfftw3@PREC_SUFFIX@_la_LDFLAGS = -no-undefined -version-info	\
-@SHARED_VERSION_INFO@
+@SHARED_VERSION_INFO@  $(ENVIRONMENT_LIBFFTW3_LDFLAGS)
 endif
 
 fftw3@PREC_SUFFIX@.pc: fftw.pc

support/BUILD-MINGW32.sh

@@ -1,6 +1,7 @@
 set -e
 
 confflags="--prefix=`pwd`/mingw32 --host=i686-w64-mingw32 --with-our-malloc --with-windows-f77-mangling --enable-shared --disable-static --enable-threads --with-combined-threads --with-incoming-stack-boundary=2"
+export ENVIRONMENT_LIBFFTW3_LDFLAGS='-Wc,-static-libgcc'
 
 rm -rf mingw32
 

support/BUILD-MINGW64.sh

@@ -1,6 +1,7 @@
 set -e
 
 confflags="--prefix=`pwd`/mingw64 --host=x86_64-w64-mingw32 --disable-alloca --with-our-malloc --with-windows-f77-mangling --enable-shared --disable-static --enable-threads --with-combined-threads"
+export ENVIRONMENT_LIBFFTW3_LDFLAGS='-Wc,-static-libgcc'
 
 rm -rf mingw64