Added #pragma STDC FP_CONTRACT OFF

Apparently, Apple's ARM compilers default to using FMA for expressions
like a * b - c * d, which causes undesirable results in Free42 and
Plus42. Specifically, (pi-pi*i)*(pi-pi*i) was producing a result with
nonzero real part in the binary builds.
Note that the x86_64 builds, iOS and MacOS, were not affected, and
neither were the Android, Linux and Windows builds.
I'm adding a #pragma to turn off this optimization, rather than the
-ffp-contract=off command-line option, so I won't have to deal with
making this change in all projects and makefiles, and having to keep
track of which compilers need it and which ones don't.

common/free42.h

@@ -30,6 +30,8 @@
 #define int8 long long
 #define uint8 unsigned long long
 
+#pragma STDC FP_CONTRACT OFF
+
 #if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 /* I have tested big-endian state file compatibility in Fedora 12
  * running on qemu-system-ppc. I found that I needed to explicitly

gtk/Makefile

@@ -29,6 +29,7 @@ CFLAGS += -MMD \
 	 -Wno-format-truncation \
 	 -Wno-class-memaccess \
 	 -Wno-unknown-warning-option \
+	 -Wno-unknown-pragmas \
 	 -g \
 	 $(shell $(PKG_CONFIG) --cflags gtk+-3.0) \
 	 -DGDK_DISABLE_DEPRECATION_WARNINGS -DGTK_DISABLE_SINGLE_INCLUDES -DGSEAL_ENABLE \