Cleanup: Simplify dependencies for GMP math header

Previously, the base math headers included GMP headers in all cases.
This was problematic because we don't want all modules that use the
math headers to depend on GMP, and the unnecessary includes could
theoretically have detrimental effects to compile times.

Now `BLI_math_mpq.hh` depends on `BLI_math_base.hh`, so if a file
needs to use exact arithmatic, it can just include the former.

Differential Revision: https://developer.blender.org/D15079

source/blender/blenlib/BLI_math_base.hh

@@ -14,19 +14,9 @@
 #include "BLI_math_base_safe.h"
 #include "BLI_utildefines.h"
 
-#ifdef WITH_GMP
-#  include "BLI_math_mpq.hh"
-#endif
-
 namespace blender::math {
 
-template<typename T>
-inline constexpr bool is_math_float_type = (std::is_floating_point_v<T>
-#ifdef WITH_GMP
-                                            || std::is_same_v<T, mpq_class>
-#endif
-);
-
+template<typename T> inline constexpr bool is_math_float_type = std::is_floating_point_v<T>;
 template<typename T> inline constexpr bool is_math_integral_type = std::is_integral_v<T>;
 
 template<typename T> inline bool is_zero(const T &a)

source/blender/blenlib/BLI_math_mpq.hh

@@ -19,4 +19,10 @@
  */
 #  include "gmpxx.h"
 
+#  include "BLI_math_base.hh"
+
+namespace blender::math {
+template<> inline constexpr bool is_math_float_type<mpq_class> = true;
+}
+
 #endif /* WITH_GMP */

source/blender/blenlib/BLI_math_vec_types.hh

@@ -14,10 +14,6 @@
 
 #include "BLI_utildefines.h"
 
-#ifdef WITH_GMP
-#  include "BLI_math_mpq.hh"
-#endif
-
 namespace blender {
 
 /* clang-format off */