package/gcc: fix fortran support

Fortran depends on libquadmath, which requires a toolchain with wchar
support.

So:
- make sure libquadmath is enable and installed when fortran is enabled;
- propagate the wchar dependency (from libquadmath) to fortran, and add
  a comment when fortran is not available.

Signed-off-by: Samuel Martin <s.martin49@gmail.com>

package/gcc/Config.in.host

@@ -111,11 +111,15 @@ config BR2_TOOLCHAIN_BUILDROOT_CXX
 
 config BR2_TOOLCHAIN_BUILDROOT_FORTRAN
 	bool "Enable Fortran support"
+	depends on BR2_USE_WCHAR # libquadmath
 	help
 	  Enable this option if you want your toolchain to support the
 	  Fortran language and you want Fortran libraries to be
 	  installed on your target system.
 
+comment "Fortran support needs a toolchain w/ wchar"
+	depends on !BR2_USE_WCHAR
+
 config BR2_GCC_ENABLE_TLS
 	bool "Enable compiler tls support" if BR2_TOOLCHAIN_BUILDROOT_UCLIBC
 	default y

package/gcc/gcc-final/gcc-final.mk

@@ -153,7 +153,7 @@ HOST_GCC_FINAL_USR_LIBS += libstdc++
 endif
 
 ifeq ($(BR2_TOOLCHAIN_BUILDROOT_FORTRAN),y)
-HOST_GCC_FINAL_USR_LIBS += libgfortran
+HOST_GCC_FINAL_USR_LIBS += libgfortran libquadmath
 endif
 
 ifeq ($(BR2_GCC_ENABLE_OPENMP),y)

package/gcc/gcc.mk

@@ -116,6 +116,11 @@ endif
 # gcc 4.6.x quadmath requires wchar
 ifneq ($(BR2_USE_WCHAR),y)
 HOST_GCC_COMMON_CONF_OPTS += --disable-libquadmath
+else
+# fortran needs quadmath on x86 and x86_64
+ifeq ($(BR2_TOOLCHAIN_BUILDROOT_FORTRAN)$(BR2_I386)$(BR2_x86_64),yy)
+HOST_GCC_COMMON_CONF_OPTS += --enable-libquadmath
+endif
 endif
 
 # libsanitizer requires wordexp, not in default uClibc config. Also