Add compile-time option -DSQLITE_USE_LONG_DOUBLE=0 to omit all attempts to use

"long double".  Or =1 to omit attempts to use the Dekker algorithms to achieve
high-resolution floating point.

FossilOrigin-Name: ca5964ef70efad3332e0bf9c158eb5fd5006d3022051d1ac506c097c427735a1

src/sqliteInt.h

@@ -4249,6 +4249,41 @@ typedef struct {
 # define Tuning(X)  0
 #endif
 
+/* By default, SQLite will use long double if the long double type
+** actually provides higher resolution than double.  This use or non-use
+** of long double is switchable at run-time by a test-control. Dekker
+** algorithms are used for high-precision floating point when long double
+** is not available.
+**
+** Having the run-time option to enable/disable long double support
+** causes problems for some compiler tool chains.  So the following
+** compile-time option is available to permanently enable/disable the use
+** of long double.
+**
+**    -DSQLITE_USE_LONG_DOUBLE=0      Omit all use of "long double" from
+**                                    the code. Instead, the Dekker algorithm
+**                                    is always used when high-precision
+**                                    floating point is required.
+**
+**    -DSQLITE_USE_LONG_DOUBLE=1      Always use long double when high
+**                                    precision is needed. Never fall back
+**                                    to using Dekker algorithms.
+**
+** If the SQLITE_USE_LONG_DOUBLE macro is not defined, then the determination
+** of whether or not to use long double is made at run-time.
+*/
+#ifndef SQLITE_USE_LONG_DOUBLE
+# define SqliteUseLongDouble  sqlite3Config.bUseLongDouble
+#elif SQLITE_USE_LONG_DOUBLE+0==1
+# define SqliteUseLongDouble  1
+#elif SQLITE_USE_LONG_DOUBLE+0==0
+# undef LONGDOUBLE_TYPE
+# define LONGDOUBLE_TYPE double
+# define SqliteUseLongDouble  0
+#else
+#  error "SQLITE_USE_LONG_DOUBLE should be set to either 0 or 1"
+#endif
+
 /*
 ** Structure containing global configuration data for the SQLite library.
 **